sounds like you went green...not sure what causes it, its happened to me a couple times though. Usually only if I'm really drunk before I smoke, then I start to smoke lots of weed...unfortunately there's not much you can do when it happens, you just have to suffer thru it. Don't go to the hospital unless you are actually passing out into unconcioussness, (ignore this if you're doing hard drugs/drinking, cuz then hospital might be better for your health) they'll probably pump your stomach and that sucks balls.

Best things I found to do is go somewhere dark and cool, drink some cold water and/or splash your face and such, to cool yourself down...try not to move around too much. Also seems to help if you have something constant to look at, with my eyes closed the spins got worse, with a focal point there was a bit of equilibrium to it. And definitely no loud music, either. and yes, chances are you can vomit when it happens, so have a bucket or a bag or summat handy just in case.

But its nothing really major; you should be fine about half an hour or so later. its mostly just a sign that you've had too much to smoke for that time, and you should probably slow down.