Hurt Arm

My 12 yr old son just made all stars and as a result of practicing alot has injured his throwing arm. He plays 1st base and the coaches are having them do drills which require extensive hard throwing. Repitious drills of throwing,(even more for 1st baseman) The sports medicine doctor diagnoised his arm as: inflamed or seperated "growth plate" which is considered like a type 1 fracture. Supposedly rest is the only cure. Can anybody let us know if there is anything we can do i.e. wrap it, cortizone shot, etc. that may help it. The Dr. recommended 4-6 wks rest which has devasted my son hopes of playing in any of the all star games. We certainly don't want him to play if there is a chance of doing any permanent damage, however how ofter does a 1st baseman have to throw the ball. Any help or advice will be appreciated.