I am so sorry about your father's suffering. And it is hard to watch our parents suffer. He is blessed to have you wanting to help him!
Apple Cider Vinegar is a good thing to try. Safe and inexpensive. Try to find raw and unpastuerized. Start him on 1 teapsoon per day in a glass of water. The next week, try 2 teaspoons per day. The next week, try 3 teaspoons per day. Times of day aren't critical--one glass in the morning and one in the evening. I just sip on my vinegar water throughout the day.
I am hoping someone else knows about dosing the Aloe, I don't have much experience with that.
Do some research on this site about Hydrogen Peroxide Inhalation therapy. It helps get oxygen to the lungs and helps with healing. We have used this for my asthmatic daughter with success.
I also bought an essential oil nebulizer for my daughter with an essential oil blend called "Lung Healing. " It has helped her a lot. I highly recommend it, though a diffuser is not cheap.
I get the oil blend here:
If you have a way to make him fresh carrot juice, that would be really good for him.
Please keep us posted on how things work for him.
~Mama to Many~