You did not mention which foods seem to cause pain after eating. Pain after eating may be a sign of many different condtions. First of all if she has severe, sharp pain, bloody stools, changes in bowel movements or fever, she should see a physician. Next is to stop intake of dairy as she may be lactose intolerant (cheese, milk, yogurt, ice cream, etc.). If that does not help she may have a condition called celic disease where gluten (wheat, rye, barley) causes inflammation in the intestines, so the thing to try is to see if symptoms improve once she is off bread, pasta, and any food with gluten. There are also specific blood and testing that can be done for the diagnosis. Best regards