Well, a lot of it depends on her actual symptoms, but if I was handed a case file with nothing more than your OP, here’s what I’d plan on telling the patient:
A hiatus, or hiatial, hernia is when part of your stomach pokes through your diaphragm and gets trapped there. It may hurt like the dickens, or it may not. It may hurt only when you eat, or all the time. It may hurt some days more than others.
Sometimes a minor case of hiatial hernia can be treated through diet and a few tips. Sometimes it gets worse anyway and you need surgery to correct it. An untreated hiatial hernia, besides causing pain, can cause gastritis (duh), esophagitis (inflammation of your esophagus, the tube food goes down in), and even shock and death if it gets really bad.
Gastritis means your stomach lining is inflamed, or swollen. It’s pretty common with hiatal hernias, 'cause the acid gets stuck in the stomach longer than it should (because the stomach is being pinched by the diaphragm) and starts to digest the stomach lining.
Take whatever medications your doctor prescribed. These will probably include something to buffer stomach acid, like Tums, something to reduce stomach acid, like Pepcid, Prevacid or Omeprazole, and maybe a pain killer as well. Take these as directed, and pay attention to what time of day your doctor wants you to take them. Set an alarm clock (cell phone alarms are great for this) and a weekly pill box to help you remember what to take when.
No smoking, caffeine or alcohol. Each of these stimulates your stomach to release acid, and will make your symptoms worse.
Lose weight if you’re overweight. Sometimes weight loss is all that’s needed to give the stomach room to sit where it should.
Eat small meals. Do not drink water or other liquids with your meals. If you’re absolutely dying to drink, take a very small sip. These reduces the size of the food in your stomach, preventing temporary worsening of the hiatal hernia because of an overfull stomach. It may also keep the contents of the stomach thicker, so they’re less likely to slosh up into your esophagus and cause heartburn (and possibly burn the esophagus.) You can drink plenty of water between meals, though.
Avoid fatty foods, which can cause reflux and slow the stomach from emptying.
Avoid any food which makes your pain worse. It’s a good idea to keep a food diary for a few weeks to see what’s what. For many people with gastritis, this means no spicy foods and, sadly, no chocolate.
Do not lie down for 1 hour after eating. When you lie down, it’s easier for gastric contents, including lots of acid, to flow up into your esophagus and give you a wicked case of heartburn. Wait until your stomach empties a bit before you lie down.
Elevate the head of your bed 6-8" at night if you get nighttime heartburn. A couple extra pillows usually do the trick, but if you sleep alone, it’s usually easier to put them UNDER the mattress, so you’re not sliding off them as you sleep.
If you feel chest pain, go to the hospital and make sure you tell them you have a hiatal hernia. Entrapped stomachs can feel an awful lot like a heart attack, so it’s good for the ER staff to know what they should be looking for to differentiate the two. A trapped stomach is an emergency, and you shouldn’t wait until morning if you feel chest pains.
Now…kidney stones… Unfortunately, there is not enough information in your OP for me to give good advice here. I don’t know what kind of stones they are, how frequently they happen, if she’s passing an active one (or more) right now, etc. GENERAL advice for those prone to kidney stones is to make sure you stay well hydrated (just remember to keep the water to between meals for the hernia/gastritis) and eliminate things from your diet that are high in whatever mineral is most prevalent in your stone (your doctor can test your stones to see what they’re made of.)
Really, really good information on dealing with kidney stones, including dietary recommendations, can be found here: http://kidney.niddk.nih.gov/kudiseases/pubs/kidneystonediet/