[Pretty boring past medical history. I'm 60 yrs old otherwise in good health exept for a past history of severe vertigo attacks (haven't had a bad attack for several years (but do have balance/dizzy/motion intolerance problems) ]

Have you had any head bumps, car accidents/whiplash type injuries in the past?
Are your neck muscles seeming tight or sore at all?
Maybe an upper cervical chiropractor might be of help.
http://www.upcspine.com/self.htm
more info- www.upcspine.com
Or if you can find an expert multi skilled chiro for assessment that might be an option.
Possibly acupuncture?