Ask a Psychiatrist and Get Answers to Mental Health Questions ASAP
Your daughter's condition is vexing. Her constellation of symptoms is quite unique, particularly given the timing of the onset of problematic behaviors. There are not any conditions I can think of that come on at age 8 or 9... they are either earlier onset (like Rett's) or later (like a psychotic disorder). In the absence of neurological disease/degeneration or medication/injury issues, I am as stumped as the doctors you have already been to.
A couple of things to consider: (a) anti-psychotic medication would only be warranted if you feel she is suffering from the delusions and/or hallucinations she is having. Based upon the brief description you provided, it does not sound as though there is distress... although the medicines would alleviate the symptoms if they ever reach that point. Your daughter's comfort is the most important consideration (as you know); (b) A more radical - and costly - approach would be to take her to a place that has premier research facilities and multidisciplinary professionals on the cutting edge of current knowledge and technology. A place like the Mayo Clinic in Minnesota has the resources to rule out a vast array of medical possibilities and arrive at a diagnosis. It sounds like a diagnosis is what would really set your mind at ease and help to formulate a course of treatment.
I wish I could have been more helpful, but complicated cases are hard to answer over the internet. I wish you and your daughter well. If you are satisfied with the response, please click "Accept." That is the only way I receive credit for my answer.