Re: Swollen painful thumb
It could also be tenosynovitis of the thumb. There are actually "tunnels" leading to each finger and the thumb, and it's possible that the tunnel leading to your thumb is affected.
I had the same problem with my thumb. It's similar to a trigger finger. After 3-4 cortisone shots over a period of a few years, it just wasn't going away any more, so when I had my carpal tunnel surgery, the doctor made a second incision at the base of my thumb and released that tunnel as well.