Sounds like a bit of vertigo. Mine started with a couple of hours in the middle of the day, and then turned into an all-day thing. For six months.
Hi, Mommie. Practically any weird feeling can be a 'side effect of MS.' I haven't had exactly what you describe, but then again these things are so subjective that it's very hard to pin them down.
I suggest you make a note of this and when it's occurred, for when you next see your neuro. It's always a good idea to keep a journal of symptoms (something I should do but often don't.) :-}
But anyway, I agree, if moving around helps, then move around.
Sending good wishes,
ess