Is my father hallucinating from his medication?
I think that you are right, that something is going on with your father. When you talk about hallucinations, that makes me think he is delirious. Delirium in older people can have numerous causes. These can include infections, medication changes, illness, or depression. What I would advise, is that you should make an appointment for your father to see his health care provider as soon as possible so that he can get checked out.
Is he taking any medication for pain? When my Dad is on any derivative of Percocet, he hallucinates to the point of hearing "things" or believing that he is a "secret agent" who is being held hostage and being poisoned by his medication!