Could Loose Tools With Blood Be Due To Medicines?

Hello, my mother is 96 years old, very healthy until last december had a heart attack, a stent was placed in her artery and two days later a pacemaker. She is doing great, never had any other problems except some pain in her back and arthritis pain. Two days ago I noticed drops of blood in her pull ups (she wears them now) Tonight her stool was very loose and in wiping herself, I noticed she had some blood. Could it be because of her meds for the heart? She is black and blue all over her arms and legs and was told by cardiologist this is the way it is? Should she have a colonoscpoy at her age? Had one many many years ago. thank you