My Mother Is 83 Years Old. I Lately Notised Decline

My mother is 83 years old. I lately notised decline in her memory ability to take her medications on time,
Confusion with the days of the week, feeding her dog and in few hours trying to feed it again forgetting that she gave her food earlier. She has tremors in her right hand but only when she picks up an object. Appetite is not good and she eats very small portions every 3 hours.
Her doctor told me this is just old age. I think this is something more and I am very concerned.
She takes 3 different medications for blood pressure ( Norvasc, Cozaar, Inderal ) and metFormin- 500mg.
I don't know if any of these meds causing memory problems. I suspect this is elzimers or dementia. Thank you, Marina.