Did you see your family doctor or a specialist?
You need to a see a dermatologist to have it looked it. They can look at it, do blood work, and maybe biopsy part of the rash to see what is going on. There are a lot of possibilities for what it could be from, but only a doctor can diagnose you.
I have gone to the doctors 3 times and I've just been given Benadryl and Minocycline. Both of which have not helped me at all.
As time passes on, this issue has gotten worse and worse. I used to only get those bumps every so often, now I get it atleast 2 times a day.
It could be an allergic reaction or heat rash. Make a doctor's appointment to get tested for allergies and have them look at it.