Why did I wake up on the floor?

Basically, I got out of bed, and I had been awake for ages. I walked to the bathroom and I felt head-rush, but I kept walking to see if it would go away. I got to the bathroom, struggled to stand up and tried to lock the door. I remember hearing banging noises and then I woke up on the floor, in a foetal position, with my feet against the shower and my back against the radiator. I said 'ow, not again' as this has happened twice. I had to stay there to let the head-rush headache go away, and I stood up, and now I'm completley fine. I don't remember anything - all i remember is walking to the bathroom, trying to lock the door, hearing noises and waking up. I dont understand how i could have got into the foetal position within seconds - well that's what it felt like. My body banged against the walls and i heard the banging, it sounded really loud. I told my mum and she's worried, she thinks I might have had an epileptic fit (i used to have epilepsy when i was younger). She said if it happens again she'll take me to a doctor, but I'm really scared now. Please can someone tell me what happend, why this happened etc. thank you.