Setting: present day United States.
I more or less know a decent amount about psychiatric evaluations and hospitalization. However, most of the information I can find has to do with situations where a person is suicidal or already has a documented history of mental illness, and I'm not sure how my situation might change things.
My character is a man in his early 30s who is suffering from hallucinations and delusions for the first time in his life. It's gotten serious enough that he's having trouble taking care of himself. He has no prior history of mental illness, and hasn't been diagnosed with any other conditions known to cause this. He's used drugs that could be connected to drug-induced psychosis, but the symptoms have lasted for days or weeks at this point and any tie to the drugs is questionable. He's also unwilling to admit to using drugs.
A friend convinces him to go to the ER.
In a situation like this, what would the doctors do? What kind of tests would they do to rule out different causes? My character is there voluntarily, but only because his friend brought him. He's neither extremely lucid nor completely willing to be forthright with the doctors -- how would this affect the proceedings?
The second part of my question is about my character's options after the initial evaluation in the ER. First of all, considering he isn't completely lucid, how realistic is it that he'd be able to voluntarily agree to stay in the hospital for inpatient treatment? What would happen if the hospital he was in didn't have sufficient space or resources? Or if he just didn't want to stay in that hospital? How would a move be orchestrated?
I really appreciate any input on this. I've tried to research it, but most of what I've found is either stuff I already know, or information about cases where the doctors already know what's wrong and the patient is already receiving treatment for it.