[moderately impaired coordination with his dominant right hand
-mildly impaired coordination for his left hand]

Was there some neck/chest/shoulder injury also?

I'm assuming you had imaging of cervical spine and no issues there that might the cause arm/hand problems.

Are you on any medications like statins for high cholesterol?
I had many odd visual, dizzy, cognitive symptoms when on Lipitor for a year...
stopped it and they went away..
Family members are on other statins and report no problems.. but I am holding off taking any..