Help! After Donating Blood...

I'm not sure if this is anxiety or hysteria or what but I was hoping someone could help me out.

While I was donating blood, I got really cold and was a bit grossed out by the needle and everything. Afterwards, I got up and felt like I was going to start crying for no reason at all. Walking to the bathroom, I erupted in laughter and couldn't stop laughing. I went back in, got something to eat (still assuming I was normal) and suddenly could not stop laughing. This laughing then turned into crying. I could not control my emotions. I was balling and could not stop. The nurses came over and laid me down and then I laughed again, cryed some more, switching between the two for quite some time and crying hysterically or laughing till I couldn't breathe. I went to the nurses office and about 15 minutes later I was fine. It was so wierd though, I had no control of my emotions. Does anyone know what this is?? Please help me!!! :d