yup most concussion symptoms are due to C1/C2 instability.. sometimes its due to the damage of your capsular ligament.it then pinches on your vertebral artery causing you a host of symptoms. C1/C2 don't have any discs ..
im having the same issues myself and so far not much has helped. ive improved in the last few months.. ive yet to try NUCCA chiropractic but ive heard positive things