Bump in wrist, and pain extending into forearm?

Sarah, the best answer to this is to see an orthopedist. A simple x-ray will determine if there is a fracture or something else such as a ganglion. A ganglion is a herniation of a tendon. The herniation will push up through the bones of the wrist and become painful when you extend your wrist just as you have stated. If this is what is present then they are going to do one of two things. The first is to aspirate the cyst, draw the fluid out of the cyst and then inject it with a fluid that should reduce the size of the cyst. If that fails to help the situation then they would have to cut the ganglion out. The danger with a ganglion is that it can force the bones of the wrist out of position making it impossible for normal functions let alone gymnastics. See a doctor about this.