Bayou,
Hey brother, my 2 cents for whatever you may consider it to be worth.
Arthritis stuff has more subdivisions than we can keep track of, but going up to the parent directory, it all falls into 2 categories. Rheumatoid style that is an autoimmune cluster fork, and the osteo branch which is just old age wear and tear. Newborn baby damages the joint with the first movement, but the body goes in and repairs. You get to my age and damage is still happening, but the repair is slower than the erosion and we break down. Realize that the pain in an affected joint or joints from osteo stuff is like the canary in a coal mine thing. Thumbs falling apart, but a harbinger of what is happening in hips, knees, spine. They just don't hurt yet but are on the verge of a painful breakdown.
Assuming you got the old age thing unless your doc said otherwise. Sounds like it is just in your thumbs and your other fingers are not warped out of shape.
You got to get yourself started on dog medicine immediately.
Realize that we got an incredible arsenal of agents and biologics to combat either condition. Hi end chemicals available if your med insurance or credit card can support. Most we can do is slow the terminal point from the traditional approved approach. Some treatments even hasten the deterioration while giving some pain relief.
Joke on the system for the osteoarthritic condition, is that the over the counter vet glucosamine and chondroiten mix not only relieves pain, but sends the joints back to a more young function if you still got viable cartilage pads in the joint. Takes awhile, like in a couple months for things to kick in, but the increased flexibility, pain reduction is because the joint cartilage interface is repairing, keeping bone on bone pain from happening. If you need dosing and timeframes, let me know. We can get you fixed for a few more years until ultimately time for you to move on to bigger and better things.
John
edited because I can't spell nothing right...