I Am Suffering From Fainting, Diarrhea, Vomiting, Upset Stomach, Please Help

I don't understand what's wrong with me. Ever since 8th grade (8 years ago) I started have fainting spells. Recently they have increased and the symptoms are always the same. My stomach starts to feel upset (like I have eaten too much) and begins to cramp up. I then break into a cold sweat and become extremely hot. I will start to have excessive diarrhea and feel as though I'm going to throw up when all of sudden I get real light headed and pass out. I'm only out for a couple seconds but when I wake up I'm extremely tired and have hardly enough energy to walk. So far this year I have experienced one of these episodes about 5 times, including today. Everything happens within a matter of minutes and it's hard to predict the onset.