My Father Has Had Increasing Signs Of Dementia In Recent

My father has had increasing signs of dementia in recent months. He is 84. But this past week, he suddenly started having intermittent problems speaking. Some times he is fine, then will go into several minutes of not being able to talk without saying his words very slowly--if at all. Was hospitalized last week for three days. Dr has run several tests. Does not think it was a stroke. But, Dad has gotten much worse this weekend after returning home. New med Dr. is trying may be the issue too. Seems to be neurological. But, onset last week was with no warning, and now seems to be increasing. Thanks much if you have observed these symptoms in a patient, and have an idea what might be going on...