Hi Canina,
My daughter went to the neurologist last week and she seemed to think she probably has a problem with her autonomic nervous system (the part of your nervous system that controls things like heartrate and breathing), which is causing the fainting.

She has ordered autonomic testing, which we won't have until Septemer. Meanwhile, she has to drink 64oz of water/day and eat as much salt as possible - the idea is to increse her blood volume, so that it gets to her brain when she stands up, more blood (and therefore oxygen) gets to her head, so she doesn't faint and get naseous.

Her guess was that my daughter had this pre-concussion, because even before the concussions, she often got dizzy and had her vision start to go black when she stood up, however, she never actually fainted. The doctor thinks the second concussion might have just aggravated her nervous system enough so that it's worse now.

My daughter has not had anything that looks like seizures. I don't know if that's any indication that what is going on with her is completely different than your son or not, but I thought I'd mention it. I hope your appt with the neurologist goes well.

Lori