what are symptoms of hypoglycemia in children

I have some some concerns that my son might have hypoglycemia.  He is a very active 11 year old.  He does not have the best diet is is a picky eater.  For some time now he has times when he "crashes".  He gets very tired, quiet, and irritable.  I have notice that if I get him something to eat he usually snaps out of it.  It happens frequently afterschool and also during basketball practice where he gets very snappy to his friends--which is not at all like him.  I used to just write it off as being tired, but a friend suggested I get him checked for hypoglycemia.

Also--if I do take him to the doctor, do I need to wait until he is displaying these symptoms, or can they check it anytime. It's hard to make an appointment when I never know when his symptoms will be apparent.

[Superbrunettecutie]

if you are worried I would take him to a doctor. Better safe than soory right?