Hi ! Good evening. I am Dr Shareef answering your query. Most likely you have got a sebaceous cyst on the skin between your scrotum and starting of your bum. This is a benign condition, but might increase in size, and could give rise to abscess due to infection. It is better to get rid of it before it complicates. If I were your doctor, I would refer you to a general surgeon who would examine it physically and decide on further management of the condition. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef.