What Causes Dizziness And Seeing Everything White?

Hi, recently i fainted. I felt dizzy and lightheaded, but that s not new to me; except this one time i started to see white spots, then suddenly everything turned white, i couldn t hear but i stayed conscious for a few minutes, i could talk, i could move for a while then i lost strenght but kept seeing everything white. Then i finally fainted. What could have caused it? Thank you!