My daughter went through similar situation!
Have you had surgery yet? I found this website on Chiari Malformation and Syringomyelia helpful www.asap.org . I Private Messaged you my email as this times out quickly. Also I am not on this site much anymore. If you want to email or PM me that is easiest for me. My daughter was diagnosed with scoliosis and wore a brace and still had rapid progression. Nine months later, after a third opinion, the 3rd pediatric orthopedic surgeon had an MRI done with results of Chiari I. He referred us to a top pediatric neurosurgeon who recommended surgery due to multiple large syrinx, spinal fluid pockets in her spinal cord due to the restriction of spinal fluid flow from the Chiari. She had no Chiari symptoms either. She had decompression surgery within months of diagnosis as we waited maximum time doctor allowed to fall over winter break. She had 2 weeks off from school so she only missed 2 weeks of school after the surgery because we were not sure how long recovery would take (was about a month). She went back after break. She was able to return to swimming within a couple months. She still had rapid progression on her curve and had spinal fusion surgery 9 months later (as also maximum doctor wanted to wait and wanted to get in summer and earliest summer could get). She went back to school in minimal time, believe it was exactly 4 weeks, with restrictions, as she didn't want to miss first day of school, and the doctor gave the okay. First surgery (Chiari) nausea due to anesthesia and area of surgery the worst, second surgery the stiffness and pain was worse, but was fine after a week and a half to 2 weeks as far as pain. She had quick recovery within 9 months fully active doing all she did before.