"They are working on the other sophomores to throw more sidearm as well." It sounds like one or more of these coaches are for some reason enamored with side arm pitching and the situation has little to nothing to do with developing your son's individual pitching ability or promoting his future success at the next level. Combined with their cavalier attitude toward his arm pain (always a red flag), I would be seriously concerned if I were in your position. I agree with other posters that step one is to talk with the coaches, and if that does not go well then the school's athletic director. Beyond that, you may not have much recourse other than to look for a different program. That sounds drastic I know but the last thing you want to do is risk serious injury to his arm at such a young age. It's just not worth it, especially if he has aspirations to play beyond high school.