Hi The buttocks are prone to develop small infections around the hair follicles, called folliculitis. This infection can go away on its own or develop into more significant infections, like cellulitis or a furuncle (boil), the later of which need to be seen by a physician because they may need drainage or antibiotics In your case it may be folliculitis, take care of the hygiene and avoid the public toilet as much as possible. when affected use mild antiseptic solution like savlon or betadine solution to clean the same and apply betadine ointment Check your sugar levels aswell to rule out diabetes since the diabetic people are more prone to get the infections or the infections takes lot of time to cure you can also take green tea if possible without sugar as it will increase your body immunity Wish You Good Health Regards Dr Sridhar K