Hello,
I am no expert so I can only tell you what I have experienced. My mother is currently 89 and has short term memory loss due to low hemoglobin. I think the hardest part for you, Ian, is to have the hallucinations diagnosed accurately. A quick doctor's visit to an elderly patient makes it a very difficult circumstance to assess. Years ago, my mother experienced hallucinations and paranoia and it took years until doctors realized she was schizophrenic. Then it took another year of trying different medications til one proved to work. Staying on the medication, kept her chemical balance in check and she has not suffered hallucinations for 20 years. With all that your mother is going through, a chemical inbalance in her brain, could be the cause. Is the doctor that came to visit, knowledgeable in mental health conditions? Does your mother later remember that she had been seeing things in her room? Can you discuss it when she is more coherent?
We are all just brainstorming, arent we!
Paulette