Children should not drink milk when they have diarrhea. Children with diarrhea may have a bad stomach, or it may be caused by gastroenteritis. If it is gastroenteritis, you should not drink milk. You can eat something light and drink some millet porridge. You can put some yam in the millet porridge. If the diarrhea is particularly serious, you can go to a regular pediatric hospital for examination and treatment. Don't delay the illness, so as not to cause more serious situations. Usually, you must pay special attention to your child's diet and health, and don't often eat some meals outside.