I was having a migraine, but the dizziness seems to be separate from that! I went to a neurologist and he thinks the dizziness/vertigo is caused by an injury to my neck sustained during the car crash that gave me my third concussion. He wants me to do physical therapy for it. This could be the answer, but I'm not sure, because I told him looking down or bending over seems to trigger the sensation, and he said he didn't think that would cause it and that it was more likely that any physical activity would trigger it. I have to disagree! Each bout of it seems to be triggered by bending over or looking down for too long. It's really hard not to bend over or look down, so I keep having it come back! Very unnerving! Just thought I'd share.