i have to agree that a VBI is the more likely explanation...sometimes radiological studies may not give a picture of the problem simply because the issue is mechanical and the actual movement is needed to show the possiblity of a kink. Arteriography may be the way to go investigation wise...with regards treatment, its best you consult both a neurologist as well as an orthopeadic surgeon to know what way to go...this is not something that a physio/manual therapist/chiropractor can handle safely without the proper investigation, I personally dont think...the risks are way too high...any loss of muscle power, funny gait, unsteadiness? etc?