###Human: I have rashes, marks and black skin inside my butt cheeks. Kindly advise. ###Assistant: Hi. I have gone through your case. You need to follow strictly a few pieces of advice. Check your blood sugar level, fasting and random, because boils occur repeatedly in it. Apply Fucidin cream two times a day on the pimple. Apply Canesten (Clotrimazole) cream in your all black area. The rash is a fungus. Keep area neat and dry after washing. Wear loose clothes and avoid sweating as much as you can.