Good luck to you and Bonnie, PQ...it will all work out if you and your son can work together for his benefit, and any help he can get to help him succeed...
You are doing the right thing by talking to the teachers...most are very cooperative when it comes to extra help either before or after school, or if they happen to have a free period when your son does...
Hang in there, bud.....
BTW, there have been studies done that show a direct correlation between studying music and music having a benefit in learning, and doing well in math and science classes...you might Google it to read more about the beneficial relationship between music success and school academics success...JMHO............