C.M.
When we started giving our daughter cows milk it gave her diarrhea and subsequently a rash. She was transitioning from breastfeeding and there is no way to do that slowly. We just had to give her a glass of milk one day. When she reacted that way we switched to goat milk which is easier to digest. After a few weeks on goat we gave the cow another try and everything came out fine. I think it just takes some time for their system to adjust. She is now a regular milk drinker and has not had any problems with it other than it filling her up. We only give milk after she has had dinner because she will not eat with a belly full of whole milk. I hope this helps and good luck.