How long does pain in forearm above wrist take to recover?

I was playing tennis for 6 hours yesterday; I play a lot but 6 hours is even a bit much for me. About four hours into the activity, I began to feel a pain in my right forearm above the wrist when I would pull my hand back while holding the tennis racquet. I played through the pain as it progressively got worse. A day later (today), the pain is still there and in fact I am having trouble with daily tasks like brushing my teeth and turning the key to start my car! I can tell it is healing, but wonder what it could be and mostly how long it will take to fully recover. I don't see any inflamation nor do I feel any pain while resting. However, my right hand is rendered useless with anything that requires even light-duty physical strength.