Not gonna lie, every time my son goes to his dad's he comes back sick. Dad usually doesn't say anything knowing he was sick. I usually text in like hey did you know he's sick? "Oh yeah he's sick sorry" is the response I get, then there goes the how long, do you know from what, what has his symptoms been etc. So all I gotta say is did you at least inform her that he was sick and what he experienced so far, low energy & throwing up? If so she had the idea in mind..if she was even caring, just seems like she was more upset. she should chill if that's the case. If I knew my son wasn't feeling themselves and throwing up I would be ready for any worsening possibilities.