I don't know about you, but even though son has come through to this point relatively healthy, with some minor issues, looking back there are things that we would change. Mostly, not starting kid pitching at 8-9 but waiting until son was closer to HS age, or perhaps in HS.
I was a parent of a young pitcher who could get kids out, I do remember those feelings of pride that he was obviously a good player and the team's star pitcher. It's normal. And it is so normal to get caught up in letting your young player do more than he should because he is who everyone wants on their team (or multiple teams). While husband was pretty pain in the a$$ about his pitching and who he played for and what he threw, we watched the other kids pitch game after game, in multiple leagues, throwing everything with no limits. Most don't play anymore, due to injury or burn out.
Better information is avaliable now and there was no HSBBW back then.
Common sense, I think there is no argument when you hurt or something doesn't feel right you stop. The first thing to teach your player, no matter what position, be honest if you don't feel well.
We all get caught up in what we feel is the best way for young players, and mostly based on our own experience, but I'll bet if you asked most parents who have pitchers or players our son's age, they to would go back and do things differently.
Anyway, this has gotten off track, for the record I never said here that throwing CB's caused injury.