Thanks for your query.
The boy most likely has tummy bug (viral infection of stomach or gut).
The smell of vomitus is of no significance .
meds & freq small sips of liquids.
Vomitings are worrisome only when the colour is coffee ground/dark brown/black or have green tinge. Also if he vomits very frequently & unable to retain anything you shoud see doctor.
Wish him speedy recovery.