John

Have you seen an experienced physical therapist about this? I was grateful that my surgeon was so gung ho on me doing PT after my ND, and while I did not have my SCM cut, there was trauma and loss of motion with throbbing pain.
It sounds a lot like muscle adhesions which either some variation of professional myofacial release may help ( massage is a very very mild form of myofacial release). Many chiropractors offer this (just say NO to the subflexion, neck cracking etc and ask for adhesion and myofacial release).
While insurance does not cover massages, it does cover PT (at least here in the USA, I do not know about Irish medical coverage).
Finally, congratulations on being clear 6 years, that makes you an undisputed Survivor.
Charm