Should I let nature take its course or intervene?

my father has alzheimers. He was taken off all blood pressure meds and heart meds and coumadin in december when hospitalized for severe back pain. The doctors couldn't give him pain meds that were effective due to his heart meds, and he was a high fall risk and would bleed to death if he fell due to coumadin. So he was taken off all those meds. Now 2 months later, his feet are swollen, and the hospice nurse says there is fluid in his right lung. He is a DNR. All paperwork filled out. The home he lives wanted to put him on diretic. I ok'd it but am wondering is this constant treating each symptom of just postponing his passing because the home wants to fix him? I wanted to say no to the nurse when she called for my permission. But since I wasn't sure if he was in pain from the swelling I said ok. When I saw him later that day, he said no they don't hurt. He doesn't walk. He is in a wheel chair or in bed. He doesn't walk anymore. I just don't know if these symptoms are his heart slowing down and perhaps letting nature take its course is a better idea. Any ideas?