25% of people with IBD will have joint pain also. Most DRs agree that treating the bowel inflammation will relieve the joint pain. I ultimately revised my meds to include sulfazine, which is an old arthritis med that works on treating both bowel inflammation and joint pain. It has more side effects than the mesalamines, though, so is not widely prescribed.
It is frustrating to have joint pain and to be told not to take Ibuprofen or Naproxen. Those are really the only OTC meds that will effectively relieve this kind of joint pain. I would suggest, again, that you focus on getting your bowel inflammation treated. For temporary relief of the shoulder pain you can try ice, or alternating ice/heat. My personal experience was that this wasn't that helpful. For many years my main complaint was joint pain and not bowel issues. I ended up seeing a rheumatologist to eliminate other autoimmune illnesses as a source of the joint pain. I'd recommend you get a rheumy on board also, but that may be more complicated given your location. Really, you should be getting your colitis treated!