Ping/blacking out after swine flu vaccine injection.?

Argh! I was at walmart mmm'kay and I got the swin flue shot and I wasn't too worried about it. After I got it things were good. I got up, not too fast either, then I started walking. I felt dizzy. Just a little bit. Then much more dizzy as blackness comes in around my eyes. I has having difficulty breathing...I felt like I was taking a nice nap until I was "awoken" by shouts for help. That's when I realized that I was indeed laying on the floor at walmart. I asked my dad why he called for help he replied, "why are you on the floor?" I merely remarked that I didn't know because I didn't the guy who gave me the shot told me to sit down. I felt like I was gonna throw up. I didn't after a while I felt fine and left. What happened? My dad told me he felt better that my eyes didn't close. But I remember seeing darkness.