No HP, keep taking damage

Hey!

I was playing around in singleplayer today when my screen suddently started shaking. It looked like I was taking damage every game tick. (1 time hurt every game tick) so I decided to try go into survival mode, and notice this:
http://i.imgur.com/pgVbzsq.png
I had no hearts! 0 HP! Nothing!

I have no idea what I did to cause the bug to get in effect. I teleported myself to 10000 Y and applied night vision + blindness until I noticed that my Y-coordinate was going negative, I didin't have a hole in the ground and it just continued! I can't remember how I got out but I somehow did. I tried to do /kill to get out of the shaking screen, but I did not die. It kept shaking and I decided to report the bug. All of this was done in Vanilla Minecraft and in Singleplayer.