Unfortunately I cannot give a clinical diagnosis over the internet
While its possible that you have a pinched nerve at the neck, this wouild have been apparent on the MRI of the neck. An EMG of the left arm and leg would be useful to document any nerve problems between the spinal cord and the peripheral nerves. Radiation can cause, sometimes delayed, nerve injury in the field of the radiation. Depending on where your radiation was given this could be a possibility, Radiaton induced damage should be visible on MRI or by EMG if involving the nerves coming out from the spinal cord. With a normal MRI, somatosensory evoked potentials can be useful at picking up abnormalities in the spinal cord and brainstem that might cause these symptoms
The swallowing may be neurological or may be related to radiation induced soft tissue injury? - have you had a scope to look down the throat?
An EMG of the left side, and medial, posterior tibial nerve and/or brainstem auditory evoked potentials (simple electrical tests of the nerves), from a neurological point of view is probably the next step in your evalaution
Thanks for all the excellent, knowledgeable, compassionate advice you have dispensed during your term. Please know your internet "patients" appreciate your hard work and wish you well in your future endeavors. With the difficult demands of your "day job" we can only admire your overtime dedication to the forum and to those in need.
Kudos to CCF and their staff!!