I'm the same. I don't care if someone else vomits unless they have a stomach virus because then there's the possibility I can catch it. Other than that, I can even take care of someone who's sick, like holding their hair back and even cleaning it up if I have to. I don't mind seeing vomit or watching movies with vomit scenes. And like you, every time I leave my house or if someone's coming over to visit, my immediate thought is "what if I vomit?" and then I feel anxious and of course start feeling queasy. I don't know why I have this thought because it never happens so I can't be of any help to you other than to tell you that you're not alone with this specific fear.