I feel a little nauseated aroun her?

I'm 17. I've been in a couple short non serious relationships. There just never has been that girl. But me and this girl now, we both said we liked each other. I really am starting to like her. We are unoffical because she wants to get to know me more. Things are going great with that. Usually im pretty smooth and im widely considered a nice guy. But this girl, i really like her. And the past two times we saw each other i felt sick to my stomach and had to excuse myself. The most recent was Friday. I was on a tight schedule so i couldnt see her long. But we were just talking, laughing, joking, etc. I had to excuse myself because i was literately on the brink of throwing up which i did very little. I came back fine. It looked like spit that i threw up. But we talked more and went outside because i had to leave. We must of hugged 8 times off and on. And i felt fine during it. I left. We started texting each other 5 minutes after. Both of us admitted we wanted more than a hug...Advice with the nervousness?THANKS