A suggestion: Put some reading material in the bathroom. Sooner or later, he'll probably get bored and reach for it.

Given that he is not open to accepting a "medical label" I suggest you look for material that represents an alternative slant. My preferred terms for the experience known as psychosis in this culture is ego collapse/fragmentation or a fragmentation crisis.

I've found a great deal of help for myself via the work of the Jungians, in particular, John Weir Perry who worked with schizophrenic individuals for over 40 years. At his Diabasis project in San Francisco, 85% of the clientele moved through their experience and stabilized without the use of any medication. The Far Side of Madness and Trials of the Visionary Mind are two titles of his that might also make up some appropriate bathroom reading material.

I would suggest you read those books as well so that the two of you will "know the language" and thus, be able to communicate about his experience. It seems to me that this is the most critical factor right now -- that the two of you be able to talk about what is happening for him. From there, you may be able to launch into a conversation regarding forms of treatment he may be open to.

Good luck.

~ Namaste