Why is my 2 year old throwing up after drinking milk

Like PP said, look into Lactose Intolerance.

Can i give my 2 year old milk after vomiting

Is he showing any other signs? Complaining that his tummy hurts or putting his legs up in the air, gassy and fussy - especially at night, or has diarrhea? If so, it might be lacotose intolerance and you should talk to his doctor about it.

My DD was about your son's age when her Lactose Intolerance started.

Unexplained vomiting in child

Toddler vomiting at night after drinking milk

1 year baby vomiting after feeding

How to stop vomiting after drinking milk

Newborn baby vomiting milk after feeding

She did fine with formula, no issue. We slowly introduced Milk, mixing it with formula like the doctor recommended and the signs started showing up shortly after a year old. She has to drink special Lactose-Free milk, and cannot eat certain cheeses (Feta and Cottage), and she has frozen yogurt instead of Ice Cream, but other than that - she eats pretty much whatever she wants.

She can have most cheeses, yogurt, eggs, etc and has no problems. The Lactose free milk is pricy, but tastes the same (actually better) than normal milk, and doesn't expire as quick as normal milk, too.