I tried to do research on if and how a traumatic event could bring on mental illness and if the illness would need to be predisposed for such a thing to happen. Not that it would necessarily be known that other members in her family had also suffered from mental illness, as she lives alone with her parents, and both are of sound mind.
The trajectory I was looking at would be for her to be catatonic immediately following the event and then from there to have hallucinations, flashbacks, triggers that set her off, and nonsensical talking, with some periods of normalcy where she can mostly act like her old self (possibly through repressed memories) before regressing again. So she can have good or bad days, depending. She's not violent but she feels threatened she'll try to escape or go catatonic again.
Not sure if this factors in, but originally her personality was very sweet, caring, sensitive, forgiving, and she believed in nonviolence. I still would like a hint of this to shine through.
I've turned up quite a lot on PTSD and schizophrenia, but I didn't know if there were any other illnesses that might be a better fit? From the symptom lists I've looked at, it seems like she would have several attributes from both disorders, but I would like to be as consistent as possible.
Searches included: mental illness through trauma, PTSD, PTSD symptoms, schizophrenia, traumatic grief, and survivors guilt
Thanks in advance for any help or insight!