Hello,
From the symptoms it can be due to chafing skin. However if it turns itchy or starts discharging then fungal infection, contact dermatitis and STD’s also need to be ruled out. Wash the areas several times with fresh water. Do not use any cosmetic products at the sites. You can apply some calamine lotion at the rash as it will help in soothing the skin. Also wear cotton undergarments. 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.
Would you be able to post some pics? Should be able to help. However difficult to make a diagnosis, just on the basis of a history.
Regards
Dr.Sasi Attili
Consultant Dermatologist