Thank you for your query.
Your granddaughter looks like having gastritis
due to some contamination.
You can give ondansetron
in prescribed dosage to control the vomiting.
Maintaining hydration is important.
Give sips of oral rehydration fluids to prevent dehydration
Monitor hydration by her activity, urine output, and skin turgor.
If vomitind are persisting, child is dull or dehydrated consult the Pediatrician
for the examination and specific treatment.
Hope I have answered your query.