Just seen this thread and wanted to respond, but I see you have already been to the GP.
I too have been having issues with my bum since early summer. Lots of blood at times - but the pain was pretty bad.
The nurse said I had an anal fissure and piles. but it was the fissure that was the really painful part. The piles were more of a pressure pain iykwim.
Mine has mostly cleared up now - I was booked in to have surgery, but had to delay as developed a dvt and am on warfarin, hence the surgeon wanted to wait.
Am glad you saw the GP- and it wasn't as bad as you thought. They see bums all the time. I have shown mine to loads of people in the past few months. Meh.
Today I had a sigmoidoscopy. The camera up the colon. Wasn't as bad as I had anticipated. It involved an enema, and seeing up the inside of my butt on a screen. Was quite interesting.
Anyway, fingers crossed yours is all okay too.
Tips - keep your poos soft - fruit is good, bananas! Water is good. Avoid codeine based painkillers. By doing these few things I really eased my fissure - and it healed up without treatment.