Is she doing it at home? What do they do when she does (reward her by giving in?).
While this can be a 'normal' phase for some kids it sounds like she is doing it a LOT.

You'll need to decide if you can handle it. I can handle poop all over but vomit is just really, really hard to stomach! Cleaning it up that often would be too much for me! I'd also be living in fear that my every move would make the kid purposely vomit to get her way.

I think it might be legit to terminate. The amount of time and effort put into cleaning up her vomit takes away from the other children.

Hopefully some other ladies have experience in putting an end to this behavior...otherwise ...