I know this is an old post. My only hope is that the original poster will get an email showing a response.
FIND A NEW NEURO.
I didn't get diagnosed until I was 38 and I'd spent a lifetime of pain, pain and more pain. Even a small Chiari blockage can cause an individual a great deal of pain. Some people have it and aren't symptomatic. Others, like me, are very, very symptomatic. I also formed a syrinx (Syringomyelia) from having the ACM1 which destroyed part of my spinal cord and made any pain I had about a 1000 x worse.
I pray you have found her another neuro that will take this more seriously. A child that young shouldn't have to deal with such pain in this day and age of advanced medicine.
www.asap.org is a great resource for Arnold Chiari Malformation and Syringomyelia.