Hi Jenni
Have you any resting splints? They are moulded to your shape and go from the tips of your fingers and almost up to your elbow - strapped on with velcro. There's a slot for your thumb too. Your hand, wrist, fingers and thumb can't move much at all. Bit like strapping a skateboard to your arm but pretty effective.
When my hands etc are playing up I wear one (can only wear one at a time for health & safety). Think that may help with your thumb pain.
Angie
Be yourself - everyone else is taken. XX