I'd call the local Women's Shelter, not to stay there but to get some resources and phone numbers. The school should be more on top of your daughter's issues than they are. You should be able to contact someone at the school district. Voices in the head could be a sign of schizophrenia, it's important to have her seen and assessed. Also call the local foster agency, again to get the name of some resources. In our area, there are Women's Services agencies to help with this king of thing. Look up that name, there might be a list of resources.
Find a psychiatrist immediately as well as a therapist; sliding scale rates or through insurance.
Another thought is that you were just coming off the "worst camping trip ever". Your daughter was apparently trying to help with the knife - and while your reaction was appropriate - it probably was the icing on the cake so to speak. 6 year old kids do not know how to deal with anger unless they have been taught so - Of course TV, is so helpful in that regard.
I guess what I am saying is that maybe she is not schizo, but perhaps stressed out being the middle child between two other kids who need a lot of help and she does not know how to deal with this. Stuttering is a definite sign of anxiety. If this is happening also at school, her teacher should be doing a referral. And this is something that should be done now - not at the start of next year with a new teacher who does not know her.
What can you do? Well, one thing is to teach her ways to communicate her anger. There is a really neat set of books aimed at this age group. It is meant to be read to them (good bonding) many times and in doing so - the child will develop (and you) ways to deal with anger. A good example and others are listed on this link is "When I Feel Angry" - http://www.amazon.com/When-Feel-Angry-Way-Books/dp/0807588970/ref=pd_sim_14_2?ie=UTF8&dpID=51btE3dscsL&dpSrc=sims&preST=_AC_UL320_SR252%2C320_&refRID=0ZHYAZ397YX7VAA8WQ9V
By the way, if you send a letter to the school principal and also the District Special Education Department saying that your child is being bullied and has a stuttering problem that is being made worse by the situation. I think you will get results. If you really want to push it - also include a copy to the Board of Education.
I really do think that getting the book I mentioned (and maybe "When I feel Sad, or When I feel Worried" and reading it to her - and maybe all your kids will help all of you.
Hope this helps!!!
Take the child to a psychiatrist ASAP! For your safety and those of your other kids. Contact her counselor at school as well. This behavior is not taught at 6yrs old. She has mental issues. I wish you the best of luck with her. Please get her help.
I imagine she got this from TV or the internet, does she have access to both? If she does, do you monitor what she watches? It sound strange but there's lot of kids nowadays who think its cool to mimick generally crazy characters, yes even as young as your daughter. But just to be safe I would take her to a psychiatrist and see if anything is wrong. Also, you are not failing as a mother, the fact that you posted this concerned question proves that you are a very caring mother just trying her best, as all have before you. Don't give up :)
Good link by mgood86 and worth reading. However, I really doubt the schizo possibility. The link mentioned above states, "The appearance of symptoms of psychosis before age 12 is rare (less than one-sixtieth as common as the adult-onset type)."
And, "Childhood-onset - Most children with schizophrenia show delays in language and other functions long before their psychotic symptoms (hallucinations, delusions, and disordered thinking) appear. In the first years of life, about 30% of these children have transient symptoms of pervasive developmental disorder, such as rocking, posturing, and arm flapping. Childhood-onset of psychosis may present with poor motor development, such as unusual crawling, and children may be more anxious and disruptive compared to those with later onset." You have mentioned none of these possibilities.
I've been through this. She needs an outlet. Ask her how she's doing everyday. There are free services for mental health in most communities. Call your local heath dept or Google it. My children do yoga and love it.