I spent some time working on an Alzheimer's ward in my younger days. I am not sure if this has been posted, However, Many of the patient's had major strokes shortly before passing, It is part of the disease being physical as well as mental. This could explain the " sudden change" in in his health, IMHO
Patients need more nourishment because their bodies deplete it guickly, and at the end, they can't even recognize themselves in the mirror.
Right now, mom will tell you she washes her hair 3 times a week....(because that's what she use to do)...
..but she won't remember to wash it at all, unless we get it done.
From what I can determine, she's in the 2nd level of the disease.....and we have her on the new medication, but she still doesn't know what day it is......whether she just had breakfast, or lunch....where she is....or anything I might have told her in the past 2 minutes.
All one can do now is be patient, and love her and hug her.