I have this on occasion. When I get out of the car, stand up fast and start walking, I get this feeling as if I have a tight helmet on. My hearing lessens, and then I get a swooshing sound in my ears.
I was told it is positional migraine, as a result of getting up quickly and moving. It doesn't happen as often as it did in the past, but it's scary. It lets up after about a minute. I have to remember to stand and wait for a half minute before moving so the blood pressure can regulate...but I always forget