My son was bottle feeding baby since he was one month old. First few months he was on formula and then we switched to normal milk. but now I have stopped giving him bottle since few days as now he is enough grown up to have milk in cup. but he refuses cup and stopped having milk totally. he eats in good amount. but since he has stopped having milk, his stool colour has changed. it is darker yellow, near to brown shade, smelly and texture like fermented batter . please guide it is normal or not.