Anal pain

I have had a pain, severe at times, in and around my anus. Sometimes it's in the buttock bones near the entrance, sometimes it goes down my left leg as far as my hamstring, and sometimes it's in the scrotum. I have had two internal examinations, a urine test, blood test and sciatic nerve checked. All my bodily functions are normal. Solids and liquids go in and they come out as they should. No problem with my sexual activity. GP initially thought it might be prostatitis, but I haven't really got those symptoms. I am inclined to think this pain is referred from somewhere, maybe my lower back or I could have some inflamation (inflammation) in the pelvis somewhere. This seems to be difficult to diagnose, so I am monitoring the situation for a couple of weeks. Anyone else had anything similar?

[remar]

I'm wondering too if this could be a lower back problem. If your spine is out of alignment it can cause pinched nerves and pain. I know you've seen your Dr and had some testing done. Have you thought about seeing a Chiropractor?