Is it possible to get concussion from shaking your own head. After shaking my head I got a bit dizzy, had a mild headache, I also felt a bit nauseous.

Possible?Yes.Likely? No.Dizziness is caused by head shaking is often accompanied by nausea(kids getting off amusement park rides experience dizziness and vomiting).These symptoms are not from concussion but are from a transient disruption of the ears balance system.You are OK.