Do you know what it is? It might be: Dermatitis herpetiformis which is like celiac disease of the skin. If you want, you could have a biopsy done. They need to do it near the rash, not on the rash itself.

Frankly, all kinds of weird skin things, rashes, hives, swelling eyelids, went away when I quit the gluten. Not going to test any theories by eating it again. That stuff is poison to many of us.