Tylenol (acetaminophen) is the only pain reliever/fever reducer generally considered safe for people with IBD. If that's not working for you, I'd try aspirin next. Ibuprofen (advil, motrin, etc.) should be avoided, if possible.
I'd also avoid Excedrin because it contains caffeine, which could irritate UC.
With all painkillers, I try to use them as infrequently as possible.