Knocking your balance "back into place" [hmmm] think that is highly unlikely to be true tbh! Your balance is managed by fluid in your ears isn't it? I was told the fluid gets in a spin and causes your vomiting centre to react.
I never heard of anyone else having this believe it or not! I've suffered on and off for years and I always suspected the GP was making it up to get me out of the office!
Anyway, I find bright lights (fluorescent esp) can trigger it, a bad shock, reading on a computer, I can't look around v sharply, can't read in car, have to sit in middle of bus. What happens with me is I get into a terrible cycle of voliting and cannot stop. I carry valoid tablets all the time and take one at the first hint of it tbh. If I don't manage to head it off, I have to go and lie down in a dark room and essentially sleep the wost of it off. An episode is usually v bad for 24-48h but can linger vaguely for a few weeks.
It's a horrible thing but manageable for me but I'm an adult and v aware of the likely triggers and warning symptoms. V hard for a child to manage it. Poor fella, I do hope it's something else. It's not life threatening but you'd definitely rather not have it.
I'd check out the shcool environment, sounds like there is something there triggering it. Are the lights v bright? Maybe if he could be seated near a window? Are they using the computer a lot? Dim the screen. If he's in the throes of an episode that hasn't been managed down, he will find it v hard to read for example. Instant nausea. Watching tv also not good.
Maybe you could ask your GP for something to help the nausea? Ginger is supposed to be a good natural remedy. But depends how bad the nausea is. As I said, they give me valoid but I'm not sure if they'd give it to an 8yo.
Hth