I am randomly fainting, any ideas?

I am a 22 year old female who for the past two weeks has been getting feelings of Deja vu and then im ping out, when i come round, im fine and remember everything, but i do have a sore head and i am tired, twice while sitting and once while standing. No reason at all for it, im not hot, doing anything excessive. I was taken to A&E as i work in a hospital, everything came back normal, blood pressure, blood tests and urine smaple. Im not pregnant, no diabetic, not eplicatic although i was told the first time i fainted i did take a fit type thing. I have been getting this Deja vu feeling for about 6 years since i was in college and my eyesight became spotty but I always thought it was because of tiderness and after a while it faded and I was fine but never fainted. does anyone have any ideas?