Hi again,
If I understand correctly, you are describing cancer that's recurred two months after bladder removal. It can happen that bladder cancer spreads that fast, yes, I'm sorry to say. If your grandfather has metastatic cancer it can also cause fevers sometimes.
It sounds like you're getting pieces of info, not the whole story. Part of the problem is that you are getting it second hand, or even third hand. And also that you aren't able to discuss things openly with your grandfather.
If you are living far away and not able to be there all the time, it might not be wise thing for you to concern yourself with every detail of what's happening. You just might have to leave it up to your mother and grandfather to deal with, otherwise you can make yourself crazy and that won't help anyone.
Sounds like the CT misdiagnosed the recur, then a PEt was done which confirmed it was cancer. I'm surprised a CT would be so far off the mark (maybe it was ultrasound?).
As for nutrition, if your grandfather isn't getting enough food in, there is the option of TPN, total parenteral nutrition, but that means getting a permanent IV line put in, and getting food through a tube in liquid form. This is also considered a 'treatment' and as such might disqualify a person for hospice, which is about pain relief and comfort, not extending life. It's a very tough choice, our family was faced with it and chose for the TPN instead of hospice because that choice was my sisters to make. She had breast cancer.
Is your mother computer savvy? If so, send her over.
All the best,
Wendy