I'm 23 and I have really bad anxiety when I interact with people. I get extremely anxious to the point I start shaking a little bit, and I constantly feel like I have to throw up. So the whole time i'm just trying to calm myself and trying to keep myself from puking.

I went to the dentist today, and as soon as they put the xray thing in my mouth, I started choking and gagging like I was gonna puke. Luckily I didn't, but I can't help but feel really embarassed about it. The lady was friendy but I also felt like she was a bit annoyed.

I'm really frustrated and tired of not being able to go out in public without feeling like I have to puke the entire time. 

How do I stop doing this?