Kuan…..I suggest that you call his doctor...no matter what he thinks about it. If you don't know the doctor's name...see if you can find it on a prescription bottle or on some of his papers.
If he is hallucinating, this is an emergency situation, in my opinion.
It is not illegal for you to give the doctor information, even if there are not signed forms. I did this all of the time, when my mother would not tell her doctor the truth....(and the doctor didn't tell my mother that I had called)…
Another option is to call emergency services....if he is a danger to himself or to you..they can take him in for a period of time, during which he will have to be seen by two psychiatrists....
Meanwhile, you can call the social worker who will be assigned to his case, and she/he can advise and help you, going forward.....