Dehydration

I need your alls opinion please, I felt very thirsty while I was waiting for my water to get cold I was drinking a pop and all of the sudden I got very light headed and dizzy and felt as if I was going to pass out. I sat down and when I got back up it came back. I'm now feeling very tired and faint. does this sound like dehydration? If so, is it bad enough to go to the hospital or just drink a ton of water?