<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have a lump the size of a hardball on my left buttock near the rectum but not in or on. It very very tender to the touch its also inflamed. Its been this way for about 4 days and hurts 247 feels like its coming to a head but is deep under skin. Please help!!!  <response>: Welcome to Chat Doctor .1. Most possible cause is carbuncle fur uncle hair follicular infective causes - bacterial infection.2. The location and symptoms suggest the acute and infective causes.3. I would suggest seeing your GP as soon as possible, depending on the size the treatment varies starting from a course of antibiotics to a small incision and Chat Doctor. You can not neglect this, as there are definitive possibilities to get complicated sinus formation fistula formation5.Take immediate action, maintain local hygiene, do not itch the area. Hope it helps you. Wish you a good health. Anything to ask ? Do not hesitate. Thank you. 