Hi Dawn,
I know your post was from some time ago, I'm not sure if this can still assist you, but perhaps it can help someone else. I am a School Psychologist currently completing my postdoctoral internship for clinical licensure. I would suggest embracing new forms of therapeutic practice (such as play based therapy) as a helpful method. Is this child able to draw? Draw any meaningful pictures? You can also communicate with graphics, or perhaps methods their school is using, to have meaningful exchanges. Choices can be great too, if they have difficulty making their own. Perhaps draw 2 pictures of options (one of dolls, one of jump rope), point, and shrug. Meeting nonverbal kids where they are at, at least to start, and minimizing verbal exchanges may be a trauma sensitive approach for them - especially if their non-verbal is a suspected result of the trauma.
Best of luck!