It could be, but it could also be simply seasonal allergy (the lungs clamping down because of allergens in the atmosphere). I would go with a physical from your personal physician first to rule out anything there. Then, I'd see an allergist with him if your personal doctor thinks it might be an allergy.

It could be so many different things. I hope you won't be overly alarmed at this point,
but I agree with everyone that you need a doctor's diagnosis to make sure your son
is okay physically.