Scary to consider, but I’d also look carefully at who is in contact with your son during the day. Is he at a babysitters before or after school? Who does he come into contact with during the day? Don’t start a witch hunt but stay alert and informed.
That’s what I was going to suggest. I’m still like this, but when I was little, my blood sugar would get too low and I’d just fall to pieces. I couldn’t describe what was wrong because I had no idea – I just felt terrible. And when I get down like that, I don’t feel hungry at all.
A substantial breakfast and/or snack might help.
I have no idea if this is true for all kids, but my nieces and nephew have a pattern where for a couple of weeks their appetites get HUGE and they could happily eat all day long – with the attendant crankiness and drama between meals. And right after that, they’ll go through a growth spurt. It’s like they have to muster up the energy to shoot up a couple of inches.
When I was about seven I had an eating problem at school every lunchtime - I had thrown up with a stomach bug for a couple of days, and was scared of eating afterwards. The teachers were pretty harsh about making us finish our meals, which exacerbated the situation, and I got worked up so much that I would refuse to eat, so was then not allowed to leave the table, so would eat a cold mess of food then would throw up with stress. This went on for weeks.
There were so many weird things going on in my head at that time that I was ashamed to talk to my parents about. It could be anything like that.
As much as I hate to say it, that does sound plausible. Abusers often say “If you tell anyone, the police will arrest you/you’ll get a spanking/your parents will hate you.” Your son could possibly be feigning the headaches so he can go to the nurse and miss Ms.* Abuser’s class. If that’s not the case, then I think it’s some hypoglycemia issue. A lot of young kids can’t go that long between meals. But most kindergartens serve snacks around 10:00, so that might not apply here.
Can kids that young get migraines? My cousin used to get them as a child, I know, but I can’t remember how old she was.
I used to get the worst migranes my last year in college, and they would happen at 11:25 AM like clock-work. I mean, you could set your damn clock by it. They’d last about forty minutes and then all would be better.
To this day, I still do not know what that was about. The cycle lasted about two months and I’ve never had another one since.
Mine started around first grade. Once a week I’d have such a bad headache I’d have to leave school, puke a few times then lay in bed perfectly still and pray I’d fall asleep. Each headache was 3-4 hours of ungodly pain and there was nothing I could do about it except hope to sleep though a good chunk of it.
They lasted (on that regular of a basis and with that intensity) until sometime in high school.
Yes, I got them that young. They were relieved by vomiting. They went away when I was about 9-10, and returned when I was in my mid-20s.
I agree with others - the first step is a good screening at the doctor for everything from constipation to diabetes.
Update:
It appears there were two different sources of the crying.
On the day when he didn’t want to talk about it, it appears that what had happened was he had been scolded by a teacher for talking in line and been made to go to the back, when he insists that he wasn’t actually talking. I remember clearly the first time I was punished for something I didn’t do by a teacher, and yeah, I cried pretty hard, so this is understandable. (I also remember crying when I was punished for things I did do, so that would explain things as well… 
)
He can’t explain why he didn’t want to tell us about this (and it took a good half hour of pestering, with me drawing out “clues” like “Okay, it was something that happened while I was in line and that’s the last clue!” to get the story) but I guess he either really was talking and thinks we’ll be disappointed or really wasn’t and doesn’t understand how to deal with the possibility that authority figures can be wrong about things like this.
I told him about the first time something like that happened to me and we had a nice conversation about it.*
Meanwhile, I think he must really have been having headaches for the ensuing three days (he just isn’t the type, as far as we and his teacher can tell, to let the incident I described ruin his lunch for the following three days). Over the weekend he got some kind of sniffly illness, so that may be related. We are prepared to go to the doctor soon–but yesterday he was fine so we’ll just keep a watch on it.
Thanks for the advice.
*My message: Often teachers have so many things to worry about that when they make a mistake like this, the kind thing to do is just comply and let it go, and really what can they actually do to you? Make you sit in a room and be quiet? Meh, just go off into your imagination if that happens. Worked for me. And one incident won’t make them think you’re a “bad kid,” they’ll know you better than that.
Hmmmnnn could be sinus infection. The dry air at school woudl exacerbate it, and the pain would probably hit just about then.
Seriously, Doctor now. How can you even consider waiting?!?
Constipation and headaches are connected.
Everytime I have a migraine, when I come out of the migraine ( if I fell asleep from the blinding pain) I ALWAYS have a very good poop afterwards. ( I wasn’t constipated at all, but the poops were effortless.) Back in the day, Doctors use to give suppostories for migraines.
When I am off in the poop department, I am off in the brain department.
Take care of your anus=taking care of your brain.
(There is an ad campaign waiting to happen.)
He had a headache for two days, and it’s been gone for three days. Sounds like it’s over.
If I take him to the doctor, she will say “He had a headache for two days, and it’s been gone for three? Ah… here overmedicate him on antibiotics or something I guess rolleyes.”
I should mention, I suppose, for context, that his doctor has on a couple of occasions in the past recommended a course of “watchful waiting” for head-cold-like problems which don’t get worse over time. So though we haven’t brought him to her for this specific problem, we are following the general tenor of her advice.
Well that’s a relief. But may I offer a tweak to your message to your kid? Kids that young don’t understand nuance. They assign traits to things that perhaps aren’t deserved and they generalize those traits to everything that object does. Sometimes this illusion is shattered and it’s very confusing for them.
One such generalization/illusion is “I saw Danny do a bad thing. Therefore, Danny is a bad kid.” This is why kids get so upset when they are wrongfully accused. They’re thinking “I’m a good kid but I’m being treated like a bad kid. That’s confusing.”
What you should discuss is not that “Your teachers know you’re a good kid.” but rather “There is no such thing as a good or bad kid. Sometimes kids do good things, sometimes they do bad things, and that’s it.” If you can get them to view the world without that label, then your kid will have a lower tendency to prejudge people, they’ll tolerate change (of, say, teachers or classmates) better, and they’ll cope with unwarranted punishment without tears.
This same attitude is how kids decide to be finicky eaters. It makes them not want to try new foods and to never try the same food twice, even if it’s cooked differently. Don’t like raw carrots? They won’t like cooked carrots. Ate a jalepeno once? They won’t touch bell peppers. So while you’re working at breaking the “good kid/bad kid” labelling habit, you might as well try it for food. Can’t hurt.
I thought that was just because migraines have the tendency to make you puke up anything you might swallow.
Thanks for the update, Frylock.
I was hoping to enlighten you with something, but it turns out to be a completely different issue. I’ve been e-mailing someone lately, and she told me that she cried every day in kindergarten. I asked her to tell me more about it, and she said she cried every day until 5th grade. She was afraid that her mother was going to forget her and leave her behind.
Looks like she’s gotten over it. 
My kindergartener started complaining last week that his cheeks hurt. We thought it was dry skin, so my wife put some lotion on his face. Same thing happened a few days later. About six days after the first incident, my wife’s sister (a nurse) was visiting, looked at him and said “Did you realize he has a fairly severe sinus infection?” 
Bad parents!
My kindergartener got sinus infections bad enough every 45 days to require a full regimen of antibiotics.
Lasted through first grade.
She’s fine now (3rd grade), but at one point lost more than 30% of her bodyweight as she simply couldn’t eat as her throat hurt too bad from PND and coughing.
They kept testing her for strep as her throat was bleeding, but it never was…
Absolutely. My son suffered from migraines all through elementary school. Turned out markers were a trigger. The chemical smell was enough to bring one on. Poor kid. Migraines can make you miserable and sick to your stomach, plus just feel wrong in an inexplicable way.