From the symptoms, various possibilities are there. These include contact dermatitis
, rash due to friction rub with clothes, dermatitis
(atopic, contact, allergic),excessive sweating causing sweat dermatitis
or balanitis(due to an underlying infection (bacterial and
fungal as well as other organisms) .
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.