From the history you give, it sounds like a overuse injury of the wrist.
Where exactly is the pain in the wrist - which side, the thumb side or the little finger side? which way does it hurt the most to move, up or down? hows your grip strength in that hand compared to the other one?
There are several other questions that need to be answered before any sort of diagnosis can be made and im afraid that can only be done by a physician.
It could one of many possible things - de quervains syndrome, a tendinitis, intersection syndrome, boxer's knuckle and the list goes on.
As to what can be done about it?
- X-rays - may show joint narrowing and cartilage wear
- NSAID - anti-inflammatory medication
- corticosteroid injections into the joint
- Wrist brace
- Rehab & strengthening exercises
- Avoiding activities that aggravate the injury
There are a few strengthing and rehab exercises for the wrist that i know about but i dont think its right to start treating something before knowing exactly whats wrong with it.
See you doctor - without a good physical examination, its going to be extremely hard/impossible to know for certain whats going on.