Sorry to hear of your husbands problems. I have experienced similar symptoms (triggered by sudden movements), and I wasn't getting answers from the clinic I was seeing. I didnt know why the symptoms kept coming back from minor things so long after the initial injury. I did a bit of a nationwide search to find good doctors and get opinions on my case. The consensus was that I have vestibular migraine. I blew this off at first because I thought, "I don't get headaches," but you don't have to get headaches to get migraine (its really a much broader disorder than most people realize), and your husbands symptoms seem to fit vestibular migraine perfectly. Just something to consider. I'd Google it and see if the symptoms match. Any sensory overload can trigger migraine pathology (quick movements counts as that). I think migraine is one of the most common PCS complications, and taking migraine preventative meds can really help.

A good place to start in terms of clinic searches (in my experience) is to see who treats your local NFL/NHL teams and try to get in there. Also, see which clinics are nationally ranked in neurology (Cleveland Clinic maybe?)

Best of luck!