Sometimes when I stand up I get dizzy and my entire body feels like there's a buzzing tingling electric sensation. There's also pressure, and a sort of pounding, but it doesn't hurt. My vision starts to go black, and sometimes it goes completely black until I can't see. To make it stop I lie down of just stand still if I don't fall down. A couple times I've fallen down, I wasn't hurt, and it was more collapsing than falling. Sometimes I sort of shake a little, I feel sort of hot and cold at the same time. But when I come back and can see again after I've collapsing, I can vaguely remember getting dizzy, but I don't remember collapsing. I can sort of remember landing on the floor, but it seems like a distant dream that I'm can't remember. I'm only out for a couple seconds at most. The tingling and pounding gradually subside, and the whole incident happens in only a minute at most.