Pain is not usually a symptom exhibited by ANs. The most common symptoms associated with ANs are vertigo or dizziness, balance problems, and hearing loss or tinnitus. The problem you described sounds more like a myalgia or muscle related pain caused by and/or aggravated by stress; the first clue was you stating that you have been working yourself hard. These are called musculoskeletal disorders and in a nutshell, that means trigger points develop within muscles (in your case, the muscle alongside and back of the neck called the sternocleidomastoid). These trigger points are like muscle knots or charley horses that form within muscles and they refer pain to different parts of the body. Different muscles refer pain to specific parts of the body. I was a TMJ specialist when I was in private dental practice (32 years) and treated many cases involving muscle disorders. My advice would be to see a physical therapist or chiropractor first since you had been treated with radiation and the success rate of that is well over 95%. If muscle therapy does not rid you of your pain, then see your neurosurgeon. You can probably not see any professional at all and try to self treat yourself at home. Muscle problems like yours respond well with moist heat but in order for it to do any good, it must be able to penetrate deeply and for at least 15 minutes so do not use hot wash cloths because they lose heat rapidly. A moist heating pad would work better. That and easing up on your work load should take care of your problem IF it is muscle related. If you see a professional, muscle problems like this respond faster with electrotherapy (High volt EGS) and massage or manipulation. Ultrasound also works but is much slower.