dont agree w getting AD or principal involved at this time. Have a mtg w coach and get on same page, son should be there too! as well as assist coaches.
State expectations based on medical facts. Tell son he has to man up and not say he wants to keep pitching and speak up if he's tired or feels any pain. Discuss pitch limits and best way to move forward.
Agree w TPM that son will be rusty for awhile. You said he Pitched 85 already this season in 7 innings. Now your upset over 68? was he tired, or frustrated over his performance? We're you noticing his mechanics changing? Did he pitch well in 85 pitch game?
Give situation one more try before going over his head to administration.
Based on the information given by the OP, getting the AD/Principal involved is warranted. One, he won't return phone calls,and two, it is a health/safety issue. 44 Pitches in one inning, and 68 in two is a heck of a lot of pitches for a fully healthy, young man. One coming off of Tommy John??