Not knowing whether you may have already been down this road...

The type of doc. I'd look for is a rheumatologist. Many want a referral from a family or primary care doc. Yet... it doesn't hurt to call around and check with the individual doc's offices. They might also be willing to work out a payment plan.

I'd also check out the American Arthritis Foundation website, and particularly this link:

http://www.arthritis.org/finding-the-right-doctor.php