"dead arm"

Dead arm or tired arm is not normal for pitchers to experience.
If your son does not feel better after a shutdown I would recommend seeing a doctor.
Make sure that your son doesn't just come back on the mound, he should be on a throwing program before he resumes pitching.

Question, why would you allow your young son to throw over 100 pitches in games?

I guess I gave too much trust into a high school coach. I did step in after his 3rd outing and worked with the varsity coach to place restrictions on his (and others) pitch counts.

I am very comfortable with his current summer team. He is a PO and well taken care of with the coaching staff...they are actually the ones who noticed his decreased velocity, etc.

Thanks for your input

Tired, dead arm is normal. Usually back to normal after a week rest, or light workout a few days later. If he's experiencing PAIN that's another matter, have that looked at. I would cutback some over the Summer.I would not have my son pitching more than once a week. If he has a long outing, then make sure the next one is not a long one too. Does 100 outings mean 100-110, or in the 120's/130's plus? How many curveballs is that in an outing? As long as he's doing those right he should be good. The fact that your asking and monitoring him shows you are being careful of his arm which is a good thing. Good luck