Rash on your butt is due to repeated infection. Your proneness to infection depends upon your body immune system which fights against any such invading agent such as bacteria, virus and fungus. There are a number of factors which jeopardize your immune system resulting in increased susceptibility to infection. Those factors include nutritional deficiency, diabetes, HIV infection, compromised skin integrity such as after surgery or trauma, excessive sweating, compromised blood circulation, congenital immunoglobulin deficiency and chronic diseases etc. Advice 1. Apply Mupirocin ointment (T – Bact ointment) thrice daily 2. Investigation – blood sugar (fasting & postprandial) 3. Wear loose cotton undergarment and clothes. Sweating predisposes infection. You can use dusting powder to keep your buttock dry. You there are too much hair in your buttock then you can trim those hairs regularly 4. Adopt proper hygienic practices such as bathing and cleaning with good quality soap 5. Take high protein diet such as eggs, meat, cheese, vegetable and fruits 6. Take proper antibiotic after culture & sensitivity report Thanks