Hi Hal,
I've gotten a similar issue before when I was doing
alot of post- hole digging by hand (using a rock bar more than post hole digger), and using pneumatic drills. I found a couple additional things also helpful.
1. acupuncture- it can be expensive if your insurance doesn't cover it but works amazingly well
2. B vitamins, for alot of nerve related pain this is very helpful, especially tendonitis and carpal tunnel
3. sleeping with a wrist brace brace: when I sleep I tend to curl my wrists in, which compounds the problem. alot of times people will wear a brace when working but actually while sleeping seems to be more important.
Hope this helps someone,