What Causes Loss Of Consciousness?

Hi, on Thursday of last week I drank with a friend of mine on basically an empty stomach. I usually don't drink alcohol since I'm 17 but I did this time...I think I had about 5-6 shots of vodka got a little drunk and then went home and slept for 3 hours that night. The next day...Friday I had a bit of a headache but was okay and went on with my day. On Saturday I went to a sporting event and started feeling dizzy. I had eaten breakfast and was well hydrated. This went on for about an hour and I felt as if I was going to pass out. So, I sat down and about 30 min later I had passed out. For the next few hours my friends would wake me up then I would pass out again. Eventually I just stopped passing out and felt okay. It was hot outside on Saturday but I am very athletic and participate in many sports and never have passed out due to heat. Any idea why this happened?