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.

Yes: the whole concept of "shaken baby syndrome" is based on this possibility.

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.