Hi How long she has this problem? What is the frequency of the poops? Does she pass normal stools too or its watery? What X ray was done? What is her weight and length now? How is her development? Please feel free to get back with the details. Mucus in stools can happen in gut infections or when she is allergic to any food ingested. Blood in the stools needs to be looked into. If associated with loose stools, it can be a gut infection. Again food allergies (especially cow`s milk protein allergy) can manifest with blood in stools. If she has the habit of passing hard stools, one needs to rule out anal fissure that presents with blood in stools. If she has loose stools, you may go in for a stool examination. Hope my answer helps you. Best wishes.