Hey dude, I am almost positive you have figured out why you had this problem, because I have had the same thing happen two times now.. Its like almost passing out/blacking out but with out losing consciousness.. kinda scary.

You probably just didnt have enough energy in your system (food/water)

This has actually happened to me too. I am almost positive that you were dehydrated or didnt eat because, both times that happened to me, that was the case! And you already mentioned not eating that day.

Just make sure you eat and drink properly now and you should not experience that again! Peace dude