Hi, Interesting profession!
Psychosis, NOS can have these symptoms, which accounts for the NOS (not otherwise specified). Some of these patients can also remain oriented to place, date, situation, but believe they are someone else and have auditory and visual hallucinations.
You might also consider someone who is under the influence of substances such as amphetamines, hallucinogens, or withdrawal from alcohol. Although, these would not be long term and would dissipate after the drug is out of the system.
Sometimes patients can have a multitude of symptoms that don't necessarily fit into any category, but they are still problematic.
Even diagnosis as common as Bipolar Disorder and Depression can have psychosis associated as symptoms, though less common.
I hope this helps. Please let me know if you have other questions. Gina
Psychotic Disorder NOS can be a temporary diagnosis, but many times the symptoms just don't fit into other serious mental illness categories, and will be tagged with the NOS specifier. In reality, true SMI patients have a multitude of symptoms that are not textbook. They are very diverse and personal, dependent upon many factors, including past and current history, values, beliefs, etc.
I love reading this type of story and of course, always critique the mentally ill characters as well. However, as long as it is not too far fetched, it is believable, and many lay people really aren't aware of how the true symptoms should be portrayed. A beautiful Mind, although may have taken some liberties, according to text book, but could be believable, and was, based on its popularity.
I do work in an inpatient hospital for the seriously mentally ill, and it is not uncommon to see patients with fixed delusions and auditory, visual, olfactory, and tactile hallucinations. Most of these patients clear with appropriate medications, but not all. And many admit and discharge with the diagnosis of Psychotic DO, NOS. So....I do think this is a believable diagnosis given the symptoms your character exhibits.
Hope this helps. Gina