Hi and welcome to the Chiari forum.
My first qiestion is- Did she have the "migraines" before the accident in 2011?
Next is a statement- Chiari is NOT the herniation of the cerebral tonsils....there is Acquired Chiari due to blunt force trauma...such as an accident.....this can cause the herniation and the same symptoms as Chiari BUT since Chiari is not just the herniation, it is NOT Chiari .
Chiari by medical definition is the malformation of the cerebral skull....in which this part of the skull is too small to contain the cerebral tonsils so they are forced out and down the foreman magmum and can cause compression of the spinal cord and brain stem. Surgery is often done to make more room to allow CSF to flow...this DOES NOT FIX OR CURE THE CONDITION.It is done to slow progression and hopefully prevent the formation of a syrinx, (cyst) that forms when the CSF flow is restricted.If there is no restriction to CSF flow surgery will not be done.
Chiropractors should be avoided with this condition even if it is Acquired Chiari since the area around the spinal cord andbrain stem is small , manual manipulations could cause something to pinch, ...so do avoid this for her until you know more.
Does your daughter have any other issues/symptoms?
Where do her headaches originate?
What area do you live in? I can send you lists of Drs to research.....
Your next step is to find a true Chiari specialist to find out just what is going on...just a neurologist may not be the right next step if the NL isn't well informed on Chiari and related conditions. You need someone that will look at the broader picture, and rule out anything else it could be.