Pain in the butt (Literally)

I have been experiencing very bad pain in the butt. Like shooting pain. I use to get it once in a while and it would cause me to tense up. But last night it started to get bad to the point when I would put pressure or push to go urinate it would hurt insanely bad. This morning I was just doing homework on the computer and suddenly I experienced the worst pain in the....rectum is that what I shall call the part that hurts?  Have you experienced this as symptoms of UC or is it something else? I'am going to the Gastroenterologist on Thursday. I just want to know if anyone else experienced it? I should probably add that I have been on remission for the past 3 months with out medication.

I've had that, never knew what it was called though. I thought it was related to my hemmies.