Ditto on the recommendation for lessons. The fiddle seems purposefully designed to mess up your body, and proper holding techniques are essential to preventing injury.

It's hard to learn that the bow is not going to fly out of your hand if you don't have a death grip on it, and we seem inclined to grip harder when trying to play fast or double stops or anything more difficult. So I'm going to recommend:

1) Rest. You are *injured.* As a sufferer from periodic (non-fiddle related) RSI, I can tell you that it will never go away for good unless you give it a chance to heal. You've been playing long enough that it won't all vanish from your head if you take a week off and then take it easy for a few weeks after that.

2) Ice if swollen or puffy looking, heat if not. If it hurts, you may wrap your wrist loosely to help retain body heat when away from heating pads and such, and kat is right -- Zheng Gu Shui is awesome stuff! I agree not to keep it wrapped tightly. It's one thing if you are a pro and you need it to get you through a session; yet another if it keeps you from giving your injury the rest it deserves.

It also helps me to do a thick but not tight wrap at night to keep my wrist mostly straight while sleeping, else I tend to wake up in paid. During the day I leave it be.

3) Evaluation by a trained instructor. You know, you might have injured yourself doing something else and your technique may be fine. But if you have developed a bad habit, it may take a lot of work to break it. In the meantime, don't push. If you can't play fast without hurting yourself, don't -- play correctly. The speed will come.

4) Have your instructor evaluate your bow as well. A poorly balanced or poorly made bow may be making a very minor problem worse. If this is the case, a fairly cheap but well made bow is the Coda Aspire, around $225 -- it's a composite, so they are all pretty much 'carbon' (hahaha) copies of each other -- you'll get more bang for your buck than you will from a Brazilwood bow for the same price.

Just my 2 penny prescription.