Just an update. The doctor found that her potassium was very low and that she has a UTI or bladder infection. We have nurses in multiple times per week and they ask all about her health, she never said a word about it burning when she pees.

So she's on an antibiotic (not the same one as last time so hopefully no problems) and potassium pills. If these don't make her feel better she will go for a blood transfusion as her blood count is also low.
After last night I wasn't sure she would be coming home, or if they would put her into hospice care. (Well, recommend she go on the basis that we couldn't meet her needs anymore.) DH even asked me if I would agree to it if that was what the doctor said.
I know things will get worse. I know that. I know that she will die. But I'm very glad those things aren't today. Even it it's only postponing the inevitable.