Pain in rectum six months after anal sex sharp pain when bm?

Anal fissure possibl. If' you've had persistent pain for six months since anal sex, you need to be evaluated by a surgeon (general or colo-rectal). If you have new pain, especially with a bowel movement you probably have a fissure. Use a stool softener (not a laxative) - colace (docusate sodium) or similar - twice a day until it's easier to go. Regardless, you should see your doctor.