The same has happen to my daughter, she is 20 months old and has been on cows milk since she was 14 months. For the past week she started throwing up after having cows milk so we stopped giving it to her she eats cheese and yogurts fine and anything else that has milk it in. I have spoken to my doctor who told me to give her soya milk instead, as she may have developed a intolerence to cows milk, the doctor said it would probably disappear again and to reintroduce her to cows milk in a few weeks, if she was then sick again to take her to doctors. The problem i have is that last night was the irst night on soya milk and she has thrown that up too.
So i dont really know what to give her, doubt my doctors will be open on christmas eve, s might just try lactose free and see if that works.