Well, Slab, the only way that I can help you from my own experience, is to say that I have BCG induced psoriatic arthritis. However, I should be very clear that you can only get THIS type of arthritis, if you already have the skin conditin of psoriasis....
Needless to say, your symptoms sound very much similar to the ones that I had, and the ones that I am still having. The thing that finally sent me to a rheumatologist was when my toe swelled up the size of a big sausage. The Doc took one look at my toe and he diagnosed me. My arthritis moves around, one minute here, and the next minute there. I am on Celebrex which does help with inflammation.
I've researched a lot about this, and what I seem to remember is that the BCG induced arthritis is temporary (????) but, what you are describing sounds like something different.
If I were you, I would get a referral with a rheumatologist. He and your Urologist may have to talk turkey!!
It's a pain, ain't it????
Take care, and please let me know how it all turns out. There aren't many of us out there with this type of response...
Rosemary