Blacking out and convulsions?

I walked over to my TV to turn it off, when I noticed warnings that I was 'blacking out'. I often 'black out', presumably because of my IDA (Iron Deficiency Anaemia). Once I realised that I was blacking out, I made sure, if possible, that I sat down on the floor, so as to not hurt myself through falling. Although I do often suffer from these, this time it was different; this time I had a state of semi-consciousness, rather than total loss of consciousness, though my senses were very, very vague. Also, with my vague partial consciousness, it seemed that I was convulsing A LOT. It was a very strange sensation. I was alone at the time, so I'm unable to gain an on-looker's perspective. I am somewhat confused and also intrigued by this very strange, and slightly disturbing experience. If anybody can, from what I've described, have a guess at what I was experiencing, that would help. Thank you! :)