I haven't experience seeing figures since I had only 1 episode in my life, and I didn't see anything out of the ordinary.
But seeing a weird shadow and being unable to move sounds very unpleasant.
In your case it happened while having important tests in your college? Because perhaps the stress caused by tests might have been the cause.
Definitely was disconcerting, to say the least. And no, it was actually mid semester, but good suggestion.