Sorry, I can't help but I know how you are feeling. My youngest had to have his appendix removed when he was only 4 years old. The operation was successful but he was very sick and so there were lots and lots of test conducted (plus a lot of pain involved). He soon recovered but now, whenever he has the slightest little pain in his stomach (like just gas), he will freak out. He is only 6.
Finally, I had the doctor talk to him. I also checked out a book about the human body and showed him where his appendic was and that since they took it out, he will never have to worry about it again.
Maybe you can have him talk to someone at the high school who has broken a bone and then returned to wrestling. Or maybe have the doctor talk to him.
Where is the 1-800-SuperNanny phone line when you need it?