Has this happend to any of you?

Alright so i've been sick the last few days, just cough and cold, nothing special. I get off of the couch to grab water in my kitchen and i guess i got up to fast? I got really dizzy, then i started to shake uncontrollably, and from what my mom saw she said i basically fell in slow motion , then i hit the back of my head on the tile floor. this is the third time this is happened, but the only time anyone actually saw it was today. i would of said something earlier but the only think i remember is shaking and falling. does this usually happen when you get up to fast?