Really Bad Anxiety plz help

Vikki
I'm Currently in high school (freshman) it's a a really good private school I wanted to get into but for the passed like 4-6 months I've had really bad anxiety and i don't know why? I don't take anxiety medications,I don't have blood pressure problems, I'm not behind there should Be no reason for the anxiety but I can sleep at night,I'm jittery,constantly hyperventilating(I'll start breathing heavy and not realizing),constantly getting head aches and getting light headed. I can't be pregnant but I'm just terrified something's wrong. Any tips?