ok, now every six months or so I have something occur. Usually what happens is i'll be at home and walking around, then i'll see blue dots until my vision turns completely blue, then i lose my balance and collapse on the floor usually paralyzed for at most a minute or two, usually just a few seconds and i'll hear nothing but very loud ringing almost like sirens in my ears. Im curious as to what this is, it happened to me last night and luckily i managed to throw myself in a chair right before i collapsed. And usually the blindness and the ringing last for 3-5 minutes...im afraid of what this might be yet i have no idea, so can anyone give me a slight guess to give me a basis on?

Thanks.