I thought I had an abscess or something not to far from my "exit". The doc drained it, and put me on antibiotics and I was fine for a year or more if I remember correctly. The next time I had trouble with it, it was filling faster than it was draining, and I had to have it removed surgically. It was actually a fistula.
My colorectal surgeon did it, but I had already been seeing him. Not sure if you have to go through your GP first.
I think only your doc will be able to tell you what it is.
Good luck!