It sounds like your blood sugar dropped or something around that. I have had that problem in th past. I remember passing out all the time in school, especially after PE. I tried to live on salads, and everything that was low calorie. Now in my adult life, I can not go for more then 3 hours with out at least munching on something small, and most my food goes to the dog, or my brother, especially when it is bad. I hope you find out what is happening, and take care of it soon, and feel better fast.