Yes you are right ,the constipation is due to cow milk. Cow milk is not recommended as a main drink or food in the first year of life. 1/-Young infants cannot digest cow’s milk as completely or easily as they digest formula. 2/-Also, cow’s milk contains high concentrations of protein and minerals, which can stress a newborn’s immature kidneys and cause severe illness at times of heat stress, fever, or diarrhea. 3/-Cow’s milk lacks the proper amounts of iron, vitamin C, and other nutrients that infants need. 4/-It may even cause iron-deficiency anemia in some babies, since cow’s milk protein can irritate the lining of the stomach and intestine, leading to loss of blood into the stools. For these reasons a baby should not receive any regular cow’s milk for the first twelve months of life. Hope you find the information useful.