How to cope with nervousness in sports??

It's starting to be a problem for me in track this year. I get really nervous before i run and almost throw up before i even run!! i used to think it was what i had eaten the day before or at lunch the day of..but it happens every meet. I try deep breaths which seems to be the most effective, i try not thinking about it and that really doesn't help because i need to think about it to get warmed up and stuff. I run the 400 and 4x4 and have decent times (52's). But i really think if i didn't get so nervous i could run alot faster. I know its adrenaline pumping but this nervousness i get almost makes me throw up and as a result slows me down. My most recent meet there was no pressure at all, we were winning the meet by far and the 4x4's the last event and i still got the same felling! I'm a sopre in high school if that means anything... any suggestions are appreciated