There are several issues in this
The best solution is to get him admitted and investigate.
Loss of appetite and weight loss
points to some serious underlying illness - infection, malignancy and so on. The typical features are often not seen in the aged.
Forgetfulness, confusion and sleepiness may mean Alzheimer - but if it is evolving faster, one has to exclude brain lesions, generally due to reduced blood supply. History of blood pressure and accident point to possible clot or bleeding at or aound the brain
is expected in this setting
And so on and on - too many to be enumerated - only an examining doctor can shortlist / There are several issues in this / The best solution is to get him admitted and investigate - it is the only way to know and treat. One should not miss a treatable disease.