Re: seeking diagnostician
It could be any of a number of problems. It could be medication side effects, a calcium problem, urinary tract infection, side effects of depression, or many other causes. I myself was having a side effect from the Statin Lipator. Once I stopped the medication life went back to normal.
With advance dementia there is atrophy of the brain which can be detected in an MRI. Yet minimal brain atrophy doesn't give a definite diagnosis and it's much better to have an earlier MRI for comparison. At this point there is no blood test used in diagnosis. Usually diagnosis is determined by ruling out the other possibilities. A geriatric neurologist is probably your best best. You absolutely need a doctor that is familiary with dementia.
When I realized there was something wrong with Mom, I took her to the Memory Assessment Research Service which is part of our local university. They are researching ways to diagnose ALZ earlier and what medications or medication combinations are beneficial. Mom had a battery of congnitive test to determine her functionality. Then she went back 9 months later for a second battery of test. By comparing the two battery of test they could tell her progress and it was absolutely downward. They obtained medication information on other causes to rule out any other possibilities and then made the definitive diagnosis. The last couple of years had validated their diagnosis.
My best advice is to find yourself a good geriatric neurologist or geriatric physician that specializes in cognitive isses. I do wish you luck and hope you find a cause of your difficulties that is treatable.