Disclaimer: I'm not a psychiatrist. So this is just resource information you can look up on the Internet, if you are still trying to pinpoint diagnosis? (Despite this thread is under "psychosis and schizophrenia".)
Stress? Some other disorder - I don't know, but it wasn't drug or alcohol related. Its the only time its happened. I prayed for my doctor to put me on the quetiapine, for years I was only on a low dose of prozac. Did God answer the prayer, or did I bring it about by force of faith, magic in a sense? I don't know. Whether its the right med to be on I don't know. I have had very grandiose ideations at times, so I don't know if they are linked to some kind of paranoid disorder?
The mind is a complicated thing and yes, certainly stress can bring on hallucinations. (A common factor in that is lack of sleep. Sleep is very important for mental health.)
Also, depending on your age, gender and other possible diagnosis like ADD or Asperger's SSRI's (like Prozac) can have side effects that cause states of psychosis. SSRI's and ADD medication for males under 25 years old; statistically speaking, a certain percentage can manifest psychotic states.
I don't know what your diagnosis is; but from what you describe; seems to me there could be a couple of possibilities. I don't know how familiar you are with the DSM either?
Psychiatry.org - DSM
So I'd certainly "second" the suggestion to talk to your doctor about the medication.
Also, this is just personal experience here. (I don't know if you are still on Prozac or not?)
My son when he was 12; was on Prozac for about 6 months and his behavior became very erratic. He tried to jump out of a second story window at school. He'd also been on different types of ADD medication; which he'd been taken off of because of severe weight loss.
My son has autism and epilepsy. He's 20 years old now and currently the only pharmaceutical medication he takes is for seizures. Mental health wise; he's stable and has been for about 7 years. He's had quite a few stressors in his life. His dad had committed suicide when my son was 15.
After the school window incident; my son had been hospitalized for about 4 days and about a month later he was having trouble swallowing after taking his evening prozac. Took him off the Prozac. Put him on magnesium, zinc and vitamin B-6 supplements. It took about 6 months for his mood to stabilize and the erratic behavior to go away, but it did and he's been stable ever since.
I have also had dissociational absences in the past, during which I had no awareness of my surroundings, or going in and out of a dissociational state, not knowing what had happened.
You mentioned "grandiose ideas". That can also be associated with bipolar disorder; which mania can manifest as hallucinations. People in manic states tend not to sleep; which is what brings on the hallucinations.
PTSD also can have disassociated states. Disassociated states where one does not remember what happened (although they are usually acting out a flashback) in their disassociated state. That happens with veterans who have "I'm back in the war" (loose touch with present reality) types of flashbacks.
So if you have family members of friends who've witnessed the states of disassociation and can describe them to your doctor; that would be useful for proper diagnosis.
Though of course more than just veterans can have "I'm back at the event" flashbacks. Those types of flashbacks can happen with any traumatic event. They happen with natural disasters, accidents and crime victims.
They can and also do happen with what's called "complex PTSD". Complex PTSD is common with childhood abuse.
There's also "dissociative identity disorder"; which the professional mental health community is divided in opinion on how "rare" or "common" it is. DID also has "loose touch with current reality" dissociative states. Though with DID they are not usually "flashbacks" as with PTSD.
DID dissociative states usually manifest in sexually risky behavior the person doesn't remember, because DID often is associated with severe childhood physical, psychological and sexual abuse.
The non-remembered disassociation states in DID usually start in late adolescence / early adulthood. Which is also the age range when schizophrenia usually manifests too.
Personally I think DID can be a "spectrum disorder"; (but not as in "Autistic spectrum" - that's a whole other disorder with a different cause of onset. ASD is a neuro-developmental disorder, just like intellectual disability, cerebral palsy and certain forms of epilepsy. Bipolar, PTSD, Schizophrenia and DID are psychiatric disorders, not developmental disorders. Thus the difference.)
I think DID can have a "spectrum" of how much the individual "looses touch with current reality" in their disassociated states. A person can develop a coping system that they are aware of, that serves the same purpose as the dissociative identities; but not loose touch with the "core personality" or current reality.
The hallucination you describe though sounds to me to be more like the ones associated with lack of sleep; (or lack of enough REM sleep). REM sleep is an issue with Schizophrenia. I don't know why schizophrenics have less REM sleep, but lack of REM sleep certainly has a connection to visual hallucinations.
Psychologically healthy people suffering from severe sleep deprivation can and commonly do hallucinate. Hallucinations are actually quite common in advanced military training like Army Rangers or Navy Seal training.
I've known and worked with people who had schizophrenia and it makes perfect sense to me that if one is seeing things that they are not sure if they are real; yes, that would invoke feelings of paranoia. That is a natural response when reality becomes blurry and does not necessarily mean the person has a "paranoid disorder".
Epileptic seizures can also cause visual hallucinations; but not like the ones that you describe. Hallucinatory seizures usually manifest as colored flashing lights or forms that resemble "grey people". Hallucinatory seizures are brief and transitory though. My son has had a few hallucinatory seizures in his life.
So I hope this information is helpful. I included a link to the DSM too.
I will pray for you and your doctors. Proper diagnosis drives appropriate treatment. I know that first hand on account of my son's epilepsy. Types of seizures can be hard to diagnose if an EEG doesn't pick up the seizure. (Which sometimes they don't!)
Medicine isn't perfect and there's a lot we still don't know. So try not to be discouraged.
