Hi, first of all make sure she is well hydrated. Give her sips of water, lime juice, coccunut water or or every 5 to 10 minutes. Dont give a large amount at a time as the child may throw up. Secondly check for diaper rash and apply coccunut oil and nappy rash cream frequently. Thirdly make sure she doesn't have any  other symptoms like abdominal click, high fever blood and mucus in stool if so consider antibiotics. Try giving ondensetrone for vomiting half an hour before feed. Avoid high milk intake