Hello,
Without examination, confirmation of a diagnosis is tough but it can be contact dermatitis, dermatitis (atopic, contact, allergic),excessive sweating causing sweat dermatitis or eczema skin.
You may try calamine lotion on the rash .You should also maintain hygiene and try to keep the area clean and dry, wear loose-fitting cotton clothing. Also use an antibacterial soap or mild soap like dove. You can also use a barrier cream with zinc oxide paste or calamine lotion or a mild steroid cream on the rash. also take antihistaminics like Benadryl for itching.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.