Same thing happened to me a few months ago, it actually happened twice. Popped 200mg of C, 24mg of E and went to the gym. About an hour later I started feeling fainty. Normally when I hit the gym on an empty stomach, weights or cardio, im usually pretty good, energy and well being. Those 2 days when it happened it felt as though I was going to die, I honestly thought I was expiring right there and then. I had to lay down in the locker room as my head spinned and felt like death. Gatorade is what saved me, my buddy ran for a bottle. Something inside of me just knew it was my insulin levels and when I popped the gatorade I felt better within 5 mins. Very scary! Also too, i noticed that even though the pill says its X mg, I dont think that is always 100% consistant. Back a few years ago when ephedrine was available absolutely everywhere the size of the pills were 25mg and they were tiny. The pills I buy today are 8mg each and actually bigger than the 25mg ones! Im thinking they range in size, one pill might be a really low dose, meanwhile another can be twice the amount.