Thanks for your query.
Some more information is required -- like
?, yellow tinge to eyes?, dark yellow urine? sore tummy
With the limited information available it could be a tummy bug or hepatitis
(inflammation of liver
Please take him to doctor to get checked. In the meantime can try 2mg dose (once only) of syp ondansetron
to control vomitings. Also continue giving freq sips of liquids to keep him well hydrated.