My oldest daughter did something like that for awhile when she was around 2 or 3. We took her off milk and put her on soy milk, then when she started pre-k she was drinking milk at school and did ok, so my Dr. had us start her on organic milk and she has been fine ever since. She can take in regular milk in smaller intervals and be ok, but too much will cause her stomach problems. My dr. said it might be a reaction to something in the milk, the hormones, antibiotics, or the processing agents. Regular milk is so bad for us, escpecailly our kids! Organics has been the way for us!