Chances are there that it is due to a fungal infection. Wash your groin daily and then dry thoroughly by pat drying, not rubbing. A hairdryer is useful if you have hairy groins. The damp groin is an ideal site for fungi to multiply. Also wear cotton underwear and change them twice a day and do not share other people’s towels. Application of local antifungal cream(terbinafine, clotrimazole, econazole, ketoconazole, miconazole) and oral antifungal drugs are the mainstay of treatment.
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.