Hello,
From the symptoms it can be dermatitis skin. Another possibility is of erythroplasia of Querat but the chances are very very less. Wear cotton undergarments and wash the area with mild soap like Dove. You can apply some calamine lotion at the rash as it will help in soothing the skin. Application of mild corticosteroid cream and oral antiinflammatories like ibuprofen/acetaminophen are also helpful. If the symptoms are severe then it will be best to consult a dermatologist
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 doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
well this has since gone away and not returned. I think it had something to do with hygiene climate and clothing. I live in the north of the very humid costa rica, its hard to shower regularly, and i would wear swim suites with netting and no underwear.