Ok help

Something that has been happening to me lately is the fact that every time I get up, I get dizzy and my vision gets blurry, like it gets all dark and I can't see, and my legs get all weak, like I can't stand at all
It used to happen only when I layed down, and the I'd stand up, but now it happens even when im just sitting down for a while and I stand up again
One time I even fainted bc I stood up too fast, like my legs couldn't hold my weight at that moment
Does this happen to any of u guys?
Should I be like, really concerned???