Can bleeding gums or ulcers cause this amount of blood on a pillow case?

My dad has been having blood on his pillow case for awhile now, and we aren’t sure what it could be. We keep telling him to go to the doctor, but he won’t go. We are worried and trying to pick our brain as to what it can be. Also, this morning when he used mouth wash and he spit in the sink, there was blood. I am worried about possible lung cancer as he used to be a chain smoker, but he has not smoked in three

years now.

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