Morphine Sulfate SR and 24 hour

My father is 81 years old and was diagnosed with colon cancer, he is also a diabetic and has alzheimers. My father was in hospital when we found out that he had cancer and that they could not operate because of his heart condition. Now he is in a nursing home where he has 24 hour a day care. The doctor has told the family last friday that he had 3-4 days left..he is still going but since they have given him morphine he does not eat or drink, he can't get out of bed and his mouth is all dry, his tongue was blackish in colour and he looks really bad, he is skin and bones now and it breaks my heart to see him like this. I was wondering if the things I am noticing about my dad is due to the morphine or what??