Contrary to popular belief babies don't need their milk--they can get calcium and protein about a million other ways. In the meantime though, rice and almond milk are great, as well as goat's milk which is closer to breast milk. In fact, if the stomach and diarrhea don't clear up soon, I'd bet money that he's having a reaction to milk. But if the doctor said the "BRAT" diet then you shouldn't give him milk because milk can irritate already upset digestive systems. Stick to pedialyte.