What you describe is a perianal haematoma, or external pile. Despite this name, it is not actually a pile at all, but is really like a blood blister such as you get on your thumb if you trap it or hit it with a hammer.

What causes a blood blister in this situation is that when the bowels are opened the anus stretches, and sometimes a tiny blood vessel will rupture and cause a leak of blood just under the skin. It raises a pea-sized swelling right on the margin of the opening of the anus. It is very tender at first, because the skin is stretched over it in this very sensitive region, and when it is further stretched by passing a stool, it is even worse.

Most of these haematomas do not need any treatment.

so you do think this will just got away over time?

I'm sure it will. Try swabbing some witch hazel on it... it works for hemorrhoids and a lot of other things. It will at least give you some comfort in the area.

thanks alot for the advice

No problem! Hope it works out.

I'm having the same problem, I never noticed there was a bump until I had a lot of pain randomally. it seemed like i wasnt in pain when I was sitting down, but other than that I was. I'm scared.

I'm going to the doctor tomorrow morning, I hope its something that will just go away. It seems to bother me a little bit more at night or whenever I get up from sitting down. It feels like stinging or just a bad sensation, and I cannot sleep.