If you can tell us more about your original concussion/s, we can give better replies.
How did you fall out of a chair to get a concussion from that?

[ I have read that minor hits and jolts can cause a concussion in a vulnerable brain.]

That applies more for violent head injuries and repeated hard hits..
Not so much for bumps or jolts..

But if you read other posts here you will notice many do have anxiety about bumps and jolts and wondering if those cause an actual concussion..
Rarely does that happen.. but anxiety can be a cause of symptoms..

Check out our sticky threads linked above this topic section and this one too-
Anxiety, bumps, symptoms , treatment info links