Dr. Hanif warmly welcomes you! Thanks for consulting at my virtual clinic HCM. I have carefully worked through your case, and can well realize your health worries. Being your physician, I want to assure, I will take care all of your medical concerns. This is fungal infection. When the sweating comes down from the back, it accumulates and makes the area of the butt crack humid. Fungus loves such areas and Tinea is the notorious fungus in this regard. This leads to what is known in medical science as Jock Itch . To treat it:- If I was your treating physician I would have prescribed you with Hydrozole Cream and Loratadine by mouth. Apply the cream on the area after cleaning the skin properly. Yes, cleanliness is the key to remain away from such problems. Use cotton-only dress (especially the undergarments). Wear loose clothes. Don t use tight jeans. Avoid hot and humid environment. Avoid unnecessary sunlight exposure. Take plenty of clean drinking water and after some physical activity (sweating) try to take a shower. Don t use scented soaps. Take shower with Oatmeal Milk and Honey Body Wash instead. It will also help get better fast. Hope I answered all of your questions. Please don t forget to add your precious positive feedback to help me able to assist you better in future too. Have a wonderful time ahead. Keep in touch for a follow-up too to let me know if you have any doubts & need further assistance. I am available 24/7 for your help. Have a blessed time ahead. Regards! DR. MUHAMMAD HANIF USA