Azus, I currently use tape on my thumb, doesn't help at all, only delays the pain. My thumb holes are also pretty large as it is right now...
My span might be an problem, but this has always been an issue for me, just latly seems to be even worse.
I'm taking a ball into the proshop guy this week to see what we can do, I just hate the feel in the ball right now and the pain really needs to stop! Keep the tips coming though, best to have more ideas of what could be wrong...