Humans should stop consuming milk when they are no longer babies, just like all other mammals. Humans are not designed to drink human milk after a certain point, and certainly not milk from another species of animal like a cow, and most certainly not cow milk that has been turned into a lifeless concoction filled with chemical and hormonal residues. Store-bought cow milk is "dead" and loaded with hormones, Antibiotics , and pus, and is heated to destroy any beneficial enzymes and other nutrients. Even raw goat milk is still milk, from another species, which only baby goats should consume and not humans. Milk is mucous forming which interferes with nutrient absorbtion of other foods. Milk produces phlegm and respiratory restrictions which might be, or contribute to why your son has trouble breathing.
As to the steroids and Antibiotics , that is at best a cover up, a treatment of symptoms that is only addressing the short term symptoms and is creating long term health problems for your son.
Also make sure he is getting enough fat and cholesterol, for instance from raw coconut oil or whole chicken eggs. A young growing brain needs fat and cholesterol for proper brain development.
By the way, a baby elephant is weaned from milk and THEN gos on to build tons of bone, teeth and tusks from the best source of calcium on the planet - greens!