Hi! You know, to give you the best answer, I think I should ask you a few questions first that will help define the problem and the situation.
Childhood Onset Schizophrenia is definitely a possibility if she is having these symptoms. You say she is hearing voices. Is this correct? Is she also delusional, like she thinks people are doing things to her or talking about her, etc.? Have you reported these symptoms to her doctor?
I need to be thorough, so let's make sure there are no developmental issues:
Has she been evaluated as being higher than average intelligence?
Does she make friends easy now and in the past? Did she always play in age appropriate ways and does she have good social skills?
Does she tend to obsess on activities she likes and have a hard time stopping when it's time to do something different?
Does she have repetitive motions and movements? Does she also have certain habits she does over and over?
Does she make facial expressions when talking, when she's unhappy or angry?
Does she have a hard time relating to other people's feelings?
Any extra information that will help, feel free to share.