<s>[INST] Hello I m am 18 years old and I ve had a soft lump on the outside of my right butt cheek but right next to my anus. It s under the skin and it does not bother me. It only gets sore when I keep touching it but it eventually goes away. I ve had it for awhile now but haven t went to the doctors for it. At first I thought it was just a pimp but then it got bigger . Feels like there could be liquid in there because it s not solid, but I m not sure. What can this be ? [/INST] Welcome to Chat Doctor .1. The history given by you suggest that it's a bacterial infection with pus collection within the lesion.2. Most possible cause could be hair follicular infection - causes like these symptoms.3.It's good if you take an appointment and let the GP examines the lump and a course of antibiotics might help. If the size is big an incision and Chat Doctor. 4. There are complications like colonial sinus / fistulas - its starts the way you are having symptoms.5. Do not scratch or press it will increase healing time, clean with antiseptic liquids, maintain local hygiene. Good luck. Hope it helps you. Wish you a good health. Anything to ask ? Do not hesitate. Thank you. </s>