Replying to So today i stood up and fainted

Alright now I know nsg isn't really the place to ask about this but, a lot of times when I'm sitting and stand up, I get really dizzy and start like blacking out. Now I usually just close my eyes and hold onto something when this happens and it goes away after a few seconds. But today it was way more intense than usual. I closed my eyes and leaned on the wall because there was nothing to hold onto, and I don't remember what happened next but when I open my eyes I was on the ground. Figured it can't be too good. Any one have any idea whats going on here? Thanks