This is just a guess. I was a gymnast/cheerleader for several years (don't make fun. ha), and I saw this ALL the time. There is a condition, though I can't remember the name for the life of me, where your can grow cyst-like material in joints that receive repetitive hits or force. For example, a gymnast who is constantly forcing her entire body weight on her wrist in repetitive, quick motions (back hand springs etc.) will often find these on her anterior wrist. They are nothing to be worried about at all. It's just a sign of stress on the joint.

This is probably a ganglion cyst. You should follow up with your doctor. They can evaluate it and make sure a proper diagnosis is made. If indeed it is a ganglion cyst they will give you options for an appropriate treatment plan.

Good Luck.

I have the same problem. I have been training gymnastics and capoeira (youtube it) and I have developed what I think is a ganglion cyst. I can't put any weight on my left wrist... AT ALL! had to stop gymnastics. I know that it started when ove training with back handsprings.
I heard that an acupuncturist can drain out a ganglion cyst.
Youtube ganglion cyst acupuncture to see. Anybody have any thoughts?