I seem to be getting a sore thumb in my casting / rod hand. The soreness is in the base of the thumb -- in the last joint and radiating down towards my wrist a bit. It's not unbearably sore, but it's bothersome enough that I'm icing my thumb and I would hate for it to get worse.

I've been fishing a bit more than usual this year -- once or twice a week for the last 6 weeks or so -- but only small stream trout fishing with a 4 wt rod.

I'm wondering if anyone has suggestions on how to deal with this. Perhaps I'm just getting old with a touch of arthritis.