I went to get my second COVID vaccine, and i have social anxiety so I was breathing hard in my mask. My mask wasn't too good, so I was breathing in carbon dioxide, and since I am ftm trans I was wearing a binder so that did not help with having to breathe. Since I was breathing in the carbon dioxide, I start to lose consciousness. Vision goes static, hearing goes cloudy, I am wobbling and swaying while standing up. I lean into the wall and hold on to the receptionist's desk, scared because I've never passed out or been near passing out, and I tell my dad I think I'm going to faint. He carries me over to a chair, I sit down, and I get that not-quite hiccup you get when you're about to throw up, and I realized. I then proceed to throw up in my mask, then seconds later throw up in the garbage.