Hello @knb2010 and welcome to the Head and Neck Cancer group. Speaking as a patient, I can say that after radiation everything is extremely slow to heal. Muscle pain, cough, difficulty swallowing are all very common and expected for months if not several years. We typically look at recovery month over month or in other words 'am I better this month than last?'. When we look at just a few weeks some things get better whilst others get worse or become new issues to deal with.
Neck exercises often help and certainly don't hurt.
The idea that a reoccurrence has taken place is a normal feeling that won't go away for perhaps decades. Even at the five year mark when the doctors tell us we are now at the safe point like the rest of the population, many of us think "Well great. That's where I was when I got cancer!"
We are here to help you through the recovery process. Many of us are very good with specific issues that are difficult to deal with when the doctors shrug their shoulders. Others most likely will jump into this discussion in time. Patients and courage in the meantime. It looks like you have good care.