Well first of all - never do CO2 and O2 tables on the same day !!!
Its written in all the beginners guides... I think you just found out why
Second - never do any breathold in water without a buddy (and one that knows what to do when you blackout). Myself I only do tables dry - out of water lying on bed.
And from what you describe it was a blackout. The shaking part was samba, but as you mentioned it all went dark and you don't really remember it definitely was a blackout.
So keep it safe man, it's not worth dying for.
