My son throws up every time he drinks milk he's okay w/ very small amount to wet his cereal (3tbsp) any more then that he throws up. can you tell why?

Yes: He does not tolerate it and the vomiting is a sign that his system does not like it. While it may not be classified as an allergy- he is reacting to it and should not have it. He will do better with rice, almond or coconut milk. I am not a fan of dairy as it bothers many people.There are other sources of calcium (sunflower seeds, broccoli, corn, supplements) and fats (avocado, olives, olive oil).