My Mother Is 95, Last Year Around November I Had

My mother is 95, last year around November I had to take her to the hospital she was ill, they did a cat scan and they saw a spot on her pancrease, they said it could be cancer. Because of her age we did not do further testing. Her stomach does give problems, but nothing that she would have to go to the hospital. But since Wednesday she has had diareha, and Friday and Saturday she was vomiting. Her stool is black, could that be from her cancer?