When you are up there in age, your health can take a permanent decline, suddenly.
My father suffered an UTI and he went from being able to function at the home to permanent mental dementia, all within a few days.
Same with my dad, 89. UTI and sepsis, admitted to the hospital on Sunday, checked himself out on Monday, back on Tuesday, died on Wednesday.
Sorry to hear this.
My neighbor (retired RN) just told me about another neighbor (aged 60) who died b/c of a UTI. It quickly spread to her kidneys, became septic and death occurred a few days later.
Yes these things can move quickly..