Brief Answer:
you should probably take him to the ER

Detailed Answer:

Hello,

although I cannot diagnose anything without examining someone in person, I can say that your description raises some serious concerns. First of all, it's usually too much for a 85 years old individual to have 6 days of fever and diarrhea. Dehydration is very likely, which impedes a big load on the kidneys. The slow thinking is a little worrisome on its own. When patients develop central nervous system symptoms like this, it may (but - thankfully - not always) indicate a serious infection.

Can you upload the test reports? The CBC and other tests may be very helpful to assess his condition. Urea, creatinine, serum electrolytes and C-reactive protein would have been the first tests to lay my eyes on in such a case.

I'll be waiting for the reports...

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Brief Answer:
please do

Detailed Answer:

Hi,

Since I haven't examined your father, evaluating the tests is the only alternative to get an idea of how he's doing. Until then there are some important clinical signs you can check yourself:
- urine production: if he's producing enough urine (more than 800 per day) then his kidneys are probably still intact. The color of his urine may provide additional clues. Too dense (dark yellow) urine usually indicates dehydration.
- blood pressure: low blood pressure may be a sign of dehydration and serious infection (sepsis)
- central nervous system symptoms like lethargy, confusion, etc: these are definite signs of serious infection and should alert you to move him urgently to the ER
- heart rate: a high heart rate (more than 100 per minute) is worrisome and usually accompanies serious infection, particularly if it persists when the patient is afebrile.
- respiratory rate: more than 25 breaths per minute is another worrisome sign which may mean respiratory distress or acidosis. Both are urgent situations and should be assessed urgently.

I hope none of the above describe your father's case!
Best Regards!

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