Well it's been about a month now doing physiotherapy to help my ailing right arm. The physiotherapist advised me to curb but not halt my piano practice. The right hand, wrist and arm are showing improved flexability and motion so that's a good thing!
I can definitely feel the tension radiating down from my neck (old whiplash injury) pulling on my right arm through the shoulder increasing much tension as I try to run through scales this morning. Left arm remains perfectly unaffected and relaxed.
I'll continue with the physiotherapy exercises prescribed and hope for improvement. Given the whiplash injury (2 of them actually, both on the job, hit from behind) date from the late 1980s and early 1990s they've had a long time to "bake in" and I don't expect they're going away any time soon so I'll have to work on developing coping mechanisms to allow me to continue to play without causing any excessive strain to an old injury.