I haven't experienced hallucinations, but I recall that my father, who had Parkinson's Disease, often reported having them, and was very disturbed by them.
The OP reference "pubmed.nih, which links to National Institutes of Health, points to reports that dopamine replacement agents used in the treatment of Parkinson disease can trigger hallucinations.
I am not by any means suggesting that Parkinson's or medications for it is the only cause, or predominant cause of hallucinations. I just found the literature of interest in my family situation.
FROM PARKINSON'S FOUNDATION