I had what you experienced last week actually, minus the hangover feeling. I smoked about 2 grams of some wicked sativa, and for the first time in years I felt like I was going to faint again.
Sounds like you just smoked too much. Next time, smoke half of what you usually do, wait 10 minutes, then smoke a little bit more if you feel like you need to. Also, dont eat it unless youre really experienced - eating it makes it about 3 times more powerful!
Try and get some different bud too, see if that makes a difference. Could just be the strain that doesnt agree with ya.