I recently tried using pinworm medicine on my skin lesions and it seems to be helping. I've also tried lice shampoo and had some relief. I had severe skin problems for a long time before I discovered I had problems in my gut as well. I would recommend trying a coffee enema just to make sure if I were you. That's how I found out and coffee enemas do help a lot.
I don't have any answers beyond that, however, I've gone to two different regular doctors and several dermatologists and they all insist it's just a harmless rash and can offer no solutions. It's really frustrating. Doctors have zero sympathy and basically blame me for causing the rash, which is ridiculous.