baby has blood in his/her stool
if you noticed blood in you baby's stool, you have to pay attention what color it is: dark brown or black, means it originated further up inside GI track. Red blood- comes from the rectum or colon. It could comes from a small tear in a rectum. Another common cause of blood in the stools of infants is food allergies. The top allergens are cow’s milk products and soy.
It's a good idea to talk to your doctor about, because it could be an infection, or a form of colitis.