I've been traveling cross country and I seemed to have fared quite well in the car once we drove for a couple of hours. Then, we finally got to San Francisco and I was fine for a day, but, then, I had this really weird vertigo. It started this morning. It feels like I'm always falling backwards. There is very little nausea, not enough to vomit. I'm just really dizzy. Does anyone possibly know what kind of stimuli puts the vestibular system in this state?