My daughter got the rota virus from another child and was vomiting for 3 days. Thankfully she was breastfeeding. I allowed her to nurse 5-10 minutes ONLY every other hour, so that she didn't have too much in her stomach at once, and was able to absorb all she consumed.
It wasn't something you ate, bacteria doesn't work like that, the baby would have had to actually consumed the actual food as well. What you eat can change the flavor and color of the milk, but most babies do not mind the variety.
The toddler probably brought it home from school and didn't show signs of illness til later because his immune system is more mature. Unless you notice her skin getting more dry, has a fever, she's not peeing at least 5 diapers worth and her eyes are a bit sunken - I wouldn't worry.