Could be anything from low bloodsugar level (did you eat/drink enough before the incident?) to a vagal collapse.
The last can happen due to heat, an alcoholic drink sinking in the wrong way or a large meal eaten too fast.
What happens a nerve, the culprit being the nervus vagus, gets overstimulated. Which lowers your pulsefreq, BP. You get dizzy, start seeing stars or black. Get all tingly and nauseous. And if all works out you collaps.
Happens to everyone from time to time.
7 out of 10 of the "respond to a patient unresponsive, pale/sweating possible cardiac arrest" seem people shook up pretty bad at the sight of their company collapsing right after they had a nice meal in a good restaurant.
Then again, I didn't see get into the spell. Didnt' see you afterwards and don't know your med background.
And an internetDoc I ain't [;)]