Yeah, I think we all do end up somewhere close to where you are at times, when things get bad. It's not a pity party, it's actually a frustrated drive to have things better ! It's dire to be so frustrated, but at the same time it is good to still have that expectation that you can and should be healthier.
I'd agree with getting another doctor - you keep going until you find one that does do you some good and will listen - but failing that, I'd be inclined to get your pain management professionals to talk to your current GI. And don't be afraid to ask her, why is she so inclined to doubt what you are taking ? (
I mean, it's not like NSAIDs are not immediately awful and excruciatingly painful for a Crohnie anyway - what idiot would take painkillers that CAUSE pain and bleeding ? !) Has she had previous experiences that make her mistrustful ? What would she need to convince her that you do have this problem ? If the worst comes to the worst, ask her outright if she is not the problem - "If I can't understand this, it must be the patient that is the problem". (I had a liver specialist that thought like that once, my blood pressure still rises when I think of her.) Sometimes that will set a doctor back on his/her heels, make them think... and if it doesn't, I say again, get another doc, what do you have to lose ?
At the end of the day, it is not what the bad doctors or other clueless people think that matters, it is what the good doctors and yourself think, and what the truth actually is.