Hi Dr Samuel. Over the weekned I was in the shower and I felt a large Knotty bump, hard to the touch on the inside of my left buttock, bordering; barely touching my anus . I told my husband and he said he could not see anything, but he definately felt it. I had a slight itch there a few days before, almost as If I had been bitten by an insect. It is a little sore, but not painful. It is below the skin. About the size of a walnut. I am a 50 yr old female. I am concerned as I have not had anything like this before. I am a MS patient on Avonex and have had bouts of stomach cramps for years, that last about an hour, before going away. I get Diahorreah, at these times; although not too severe. These symptoms occur about once a week for a a while, then i can go go 2 - 3 weeks where I am ok. This knotty lump is hard, almost like a fatty lump? It is static, it does not move at all. It seems to be flat, but runs quite deep. My neurologist said he thought i had irritable bowel . This lump seems to have apperared belowthe skin in the last couple of weeks, as I do not think it was there beodfre that. Thank you. Tina