First of all, keep in mind that I am unable to diagnose you because I am unable to examine you, this forum is for educational purposes.
The symptoms that you describe are consistent with occipital neuralgia. This is non-specific for the cause (common causes include old neck injury(whiplash, etc), vestibular problems, cervical disc disease, etc), but results in the pinching of a nerve that supplies cutaneous innervation of the occiptial region (supplies nerve supply to the skin over the back of the head). This nerve is called the greater occipital nerve, and is a common tender point in patients with necks problems and headaches. This nerve is part of the input into the system that triggers headaches (most often in migraine headache prone people, but also in others). First I would recommend an MRI of the cervical spine to evaluate for a structural cause (cervical disc disease, compression fracture, etc). Then I would recommend neck physical therapy and a headache preventative medication such as tizanidine (Zanaflex) elavil, or topamax. If your symptoms do not respond to this, than trigger point injections into the greater occipital nerve can provide some temporary relief (can be provided by a neurologist that specializes in headache).
I hope this has been helpful.
I have been following this board for a while and notice you post a lot. Need some help with my problem and would appreciate your input. How did you determine your problem was muscular? Background, in 2003 I had neck, back and rib pain. After months of this finally had MRI, showed herniated cervical disk. Had PT for about three to four weeks, during one session the PT pushed on spine thorsic area and pain in back was gone. I think the reason it took so long to find pain was because I had arthritis (not sure of the medical terminology) in ribs all on my right side which was causing pain in front and back and everywhere on my right side. Fast forward. I was rearended in car accident in November of 2006 and have been in constant pain since all on my left side this time. The newest MRI shows mild left side nerve pinched at C6-7. My problem is left side pain in upper back, varies from burning pain (feels like sunburn) to aching, to down right hurting along with left arm problems from elbow down, wrist and left index finger. I just had my second cervical epidural yesterday - first one I felt small relief in back and some relief in left arm but when pain returned, left arm is worse than before. I also have been trying trigger point massages as well as exercising back muscles. Nothing seems to help. Would like you input.