osgood schlatter

My son was recently diagnosed with osgood schlatter’s in both knees.
He has a terrible time and he does play alot of sports.
He is currently in football.
The Dr. seemed to think it really wouldn’t matter if he played. Just to use RICE therapy after the fact.
He has him taking two ibeprophen 3x a day.
We just recently got him knee bands that are suppose to take the pressure off.
He has now been having problems with his knee giving out but not forward it goes backwards not extremely but enough to cause alot of pain.
Is this normal with osgood? Or is this another problem altogether? The sports he is involved in are basketball, baseball, and football.
I read an article that stated certain excersise for the hamstring and quad would help but he does both those in warm ups for football.
What else can we do and refuses to give up his sports but will it cause more injury to occur? Thanks for any help or any information you can give me.
I also read that vitamin E and selenuim would help with OS.
Is this true?
I just can’t believe that this disease has been around for so long and no one really has found anything to really help.