<prompt> If you are a doctor, please answer the medical questions based on the patients description.noticed a small hard lump at the top of my butt crack a couple days ago. It is now becomming longer, spreading downwards through my butt crack, and becoming more painful. The skin is tight and leathery around the lump. It is uncomfertable to sit down in some positions.  <response>: Hi, If youre between 14-45, then youre probably suffering from an infection at the top of your interglacial crack. In medicine its called Colonial SinusCyst. This is a congenital cyst that can get infected by ingrowing hairs. We see this more in men than in women and more in men with a pretty big hair growth. For me as a surgeon, the only permanent solution is surgery. I see a lot of GPs prescribing antibiotics, but most of the time it doesnt work or will return. So surgery is needed in order to Chat Doctor. There are several surgical techniques to do this. So I would recommend you to see a general surgeon who can fix this problem. Hope this helped. Let me know if I can assist you further. 