Whenever I was in a bad flare, my joints would also get very stiff and sore, so much so that it was difficult to get up off the floor after playing with my kids and was tedious to climb steps. Each flare carried with it different joint pains...sometimes wrists, sometimes knees,etc. Talk to your doctor, but what mine said was essentially that people with uc can develop arthritis during flares. Both diseases are related to the body's immune response which is why uc and arthritis often go hand in hand. I never had arthritis before having uc though see why they are correlated. While on prednisone, my joints always felt terrific and after tapering off, pains often would return. See if there is anything your doctor would recommend for the pain as you can't take ibuprofen. I'm about to ask my own doctor the same thing because my right leg and hips are soar all the time. Good luck.