More and more children are turning up with either an allergy or an intolerance to dairy products. Coughing, coughing up pflegm, sounding like they're congested and/or have a cold, runny nose from "allergies," having asthma...the list of symptoms goes on and on. I would advise any mother who has a child who is having a chronic cough and/or being really pflegmy to take their child to see a naturopathic doctor and have the child tested for dairy (cow) allergy (to proteins casein and whey) or dairy intolerance (to lactose or one of the other sugars).
Before I had a food test taken at the age of 40, I was unaware that I had a casein allergy. Once I quit eating all cow dairy (I can eat goat or sheep, but not soy), the chronic rhinnitis and sinunitis issues, the allergis, and the asthma I'd dealt with most of my life went away. Another mother on Mamapedia just took her 3-year-old son in to have him food tested at a naturopathic doctor, and he came back with allergy to both casein and whey proteins in cow milk as well as intolerances to egg, wheat, gluten, peanuts, soy, garlic...and a believe a few others.
Food allergies and intolerances do not go away, and will continue to have devastating effects on health if they are not addressed. I know; read through my backlog of comments if you want to know the struggle I've had to get healthy. Eliminating foods that didn't agree with my body was the biggest step I could take. Good luck.