I brought what I thought was the healthy child to Walmart with me only to have this happen.
Luckily all my kids got sick on the same day, just at different times. So while it was a lot of fun (sarcasm) to clean up vomit (and in Griffin's case diarrhea) all day (especially when your own stomach is a little on edge) it was over quickly at least. And honestly, the silver lining of having your child vomit all over the floor in Walmart is you don't have to clean it up. Perk.
To be fair, we were literally running (from the line where I had tums in hand) to the bathroom when it happened, and I did ask the grumpy employee if I could help in any way. They sneered a 'no' at me.