sekio - you sound like my pediatrician from when I was a kid. "Um doc, my back hurts after I'm done practicing backflips in the halfpipe." "Don't do that then." "Hey, I think I have tendinitis of the elbow from throwing down to 2nd base." "maybe you should play golf instead."
Fuck that guy.
It is the powder getting into your throat/ airways and your body's response. When you snort things, try to keep your mouth open which will force your body to close that little flap that lets stuff through your nose into your throat.