Here, let me… ah, never mind.
it could be something at the hospital. When I was an NA, I got rashes from the stupid hand sanitizer we had to use every 30 seconds. I’d rather just wash my hands constantly than use the hand sanitizing foam. Plus I eventually I found out I am allergic to Icy Hot, so no more muscle creams for me.
Also, I get weird spontaneous rashes as well, and I just chalk it up to hormones. I have PCOS and now I am pregnant, so weird unexplainable rashes come with the territory. I take benadryl to sleep and maybe put benadryl cream or cortisone on during the day.
I have had a reoccurring rash under my right arm, in the arm pit area for almost 15 years now. I went to the dermatologist once, they tried to diagnose it as a yeast infection, even tough I kept explaining to them cortisone is the only thing that gets rid of it, and I was given a anti-yeast cream, which of course just made it worse because I wasn’t using the cortisone, so I totally support your decision to not waste time at a doctors. You know what relives it and it is likely not an indication of anything serious, just a sensitive immune response.
You’re too kind. 
I do home nursing. I suppose it could be something in someone’s home, although I don’t spend a lot of time with my boob hanging out. (Not that kind of nursing! Har har.) But maybe something gets under my nails and then I touch me… Well, if that’s it, there’s really no identifying it, so I’ll just deal. And wash my hands more.
YAY! And may you never experience PUPPP. I did. Ugh.
Oh, I do have that a little bit, on my arms and legs as of right now, but I am starting to get it on my belly. I just live off of benadryl so I can sleep some nights, 
Some liver problems can cause itching. I seriously doubt that’s what it is in your case, but thereya go.
Maybe a vitamin deficiency?
IANAD.
Yeah, I’d heard the term “cholestasis of pregnancy” from the various pregnancy books. I didn’t recall the details, but recalled that itching was one of the major symptoms and sometimes it required delivering the baby early.
And I remember thinking with contempt “deliver the baby early? just for itching???”.
If there’s a God, s/he’s got a really nasty sense of humor. I developed what I presume to be cholestasis, because of my gallbladder issues (I imagine a gallstone was basically causing a blockage)… and oh. my. gawd the ITCHING. To this day, when someone tells me their gallbladder attacks were worse than childbirth, I say “meh, sure the pain sucked, but the itching was far, far worse”.
From here:
This pattern doesn’t sound like WhyNot’s symptoms but it certainly couldn’t hurt to discuss it the next time she’s at the doc. Maybe get a standing scrip for some bloodwork to be done the next time you have a bad flareup?
I tend to use zinc and castor oil cream on my various unknown source itchiness - works for me but ymmv
If it starts with annoying itching when you take your bra off at night, what happens when you go a whole day without wearing one? Or, have you tried leaving it on overnight?
Anyway, I’m of the opinion that testing an elimination diet would not hurt. I know several older women who, while not full-blown celiacs, felt better in a variety of ways after cutting wheat from their diets.