Conversation: The conversation between human and AI assistant.
[|Human|] I have a lump about the size of a small marble that is under the skin on my right butt cheek.  It has been there for about 2 years and about 3 days ago I noticed that it had gotten bigger and was sore when touching.  When looking at the area you cannot really tell that there is a lump under there
[|AI|]  Hi! Good evening. I am Chat Doctor answering your query. From such a long duration history, it seems to be a benign lesion like a sebaceous or Desmond cyst which has now got infected giving rise to the pain and increase in size for the last three days. However, it can be confirmed only by physical examination by your treating doctor. If I were your doctor, after physically examining you I would prescribe a course of antibiotics for you along with an anti-inflammatory Chat Doctor.  Once they infection subsides, I would refer you to a general surgeon for an excision biopsy of the lesion, which could either be curative or diagnostic. 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 Chat Doctor to clear doubts on your health problems. Wishing you an early recovery. Chat Doctor.