I had a lot of joint pain from uc, long before the intestinal symptoms showed up. Trying to get my doctor on the same page about an inflammed knee too painful to walk on was an exercise in frustration and futility, so I totally understand where you're coming from.
For a lot of reasons, doctors don't help manage pain very well, and you may need to find a specialist who deals only in pain management.
I would suggest, however, that you take your pain medication as prescribed. From a doctor's perspective, you complain of pain and are given a script for pain relief which you tell him you do not take or do not take completely. Dismissing your concerns isn't right, but not taking the medication as prescribed may have the doctor questioning your degree of pain or questioning whether you are drug seeking.