Please help. I am a 56 year old female, and I saw blood on my underwear, on the back, where my anus is. But i have more problems.. i feel pain in my lower stomach, my stool is loose and dark, sometimes narrow, sometimes in the shape of little balls. It always changes. there are periods of normal stool, but from time to time, my stool changes. I have had this pain in my lower stomach for days, and seeing my stool dark and loose is really scary. Please, help me. Could there be anything else but stomach cancer?