Neck pain that is one sided has the differential of facet disorders and nerve root disorders. It is unlikely that disc pain by itself will cause this pain.
You have central spinal stenosis-relatively significant at C4-5 and moderate at C3-4 and C5-6. This is a problem with spinal cord compression that can lead to myelopathy or central cord syndrome (see website).
You note these symptoms occur with extension only. Did you have one of those Fonar MRIs that records motion? If so, these images are generally not very good or diagnostic for the most part. There is also no comment on the size of the foramen at each level. This is necessary to determine what nerves could be compressed.
The most immediate attention should be brought to the spinal canal stenosis. The neck pain can be diagnosed by either SNRBs or by facet blocks (see website).
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.