I am really sorry that you and your dad are going through this. I can only reply on the sepsis infection, and it may not be much help. My husband had sepsis last year at this time. He had 0 white blood cells, 0 platelets, and only a few red blood cells due to a cancer drug that was given to him in excess. Thus he got sepsis. (had blood infection, lung infection, c-diff (stomach and intestinal infection) He was given an IV drip of a broad spectrum antibiotic. This once a day through an IV. He was hospitalized for almost two months dealing with infection after infection. He made it through though, and is healthy today.
I feel for you. Guess I replied mainly to tell you that in dire situations, there is still hope. Don't give up. Be an advocate for your dad. Stay by his side, continue to ask questions, and seek answers.
You are in my thoughts and prayers.