Hello,
Thanks for posting your query .
Your son most probably had a bilious ( bile )vomiting .the bile is a greenish secretion and whenever there is an obstruction or infection in the gastrointestinal tract( gut) it may not be utilized properly and pools in the stomach and small intestine which can cause pain and vomiting .
Sometimes the cause in children could be minor like indigestion ( junk food etc) or a viral infection in which case it should resolve on its own within a day or two. But if it persists or child gets worsening symptoms like fever, colicky pain, vomiting diarrhoea or blood in stools then you have to get him evaluated for significant causes like bacterial or worm infection or obstruction to the gut.
As of now if your child has no pain or vomiting or diarrhoea after the first bout of vomiting then you need not worry at all . All you should do is keep a watch for any new symptoms and consult his pediatrician promptly if they do worsen.
Also I would recommend regular deworming of the child with antihelminthic medicines like albendazole etc as per his doctors prescription .
So please do not worry and make sure you give plenty of water and a easily digestible (less oily & less spicy )fibre XXXXXXX diet like cereals with XXXXXXX leafy vegetables , soups , etc for better relief.
Hope I have answered your query.
I'll be available for any follow up queries .
Kindly accept my answer in case you have no further queries.
Regards

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