Hi Joanne,
I fainted a lot in the aftermath of my concussion. When I thought about it, it seemed to happen when I got up or tried to move my head too quickly. (Curse you exaggerated tbi startle reflex!) It turned out that (like a lot of tbi folks) I have PCS induced blood pressue issues and nerve damage in my neck. You might want to see a good neuro-chiropractor. PM Mark in Idaho, he knows loads about that.
Yes, those old chestnuts "depression" and "anxiety." They are terrible
symptoms of PCS; they don't cause PCS.

Imagine if depression really did induce fainting. Please, there'd be so many folks out for the count that you could walk down the sidewalk without your feet ever once touching the pavement.
It's pathetic how little most doctors know about brain injury. It's evil how little they care about brain injury patients.
Cheers