Interesting stuff, the foregoing.
I have suffered intermittently from the medical condition of vertigo since 2003, when I picked up a virus in Morocco, probably from the swimming pool in the riad we stayed in (probably not clean enough, and I'm a very poor swimmer, work it out) that spread to the coil in my inner ear.
I get attacks about 3 times a year, it comes without warning, when I sit up in bed in the morning, and suddenly the whole world is spinning around sideways. I just collapse back on the bed again and cling on tight in case I float away! It's quite frightening. I also feel nauseous as well. It lasts up to a week, during which I have to move about really carefully in case I fall over.
It led to me having to take early retirement (not that I was sorry!) because I was considered to be at risk driving company vehicles. I'm more likely to get it after flying, and in hot weather. The good news is, I don't get it at altitude, i.e. up in mountains. Something to do with air pressure, maybe?
The other form you have been discussing is fear of heights, commonly called vertigo, but something different altogether. I've never liked climbing ladders - or crossing Crib Goch! - and if I look down at a big drop my knees go weak and I've got to hold onto something. I think this originates from me being lanky and clumsy - my feet get in the way of each other, and I'm frightened of tripping or slipping. My experiences in the mountains over the years have helped to improve this a bit, I'm much bolder than I used to be..