Here is some info I have found along the way from doctors and reading medical studies. (Pubmed is a great gov. site.)
Generally, sensory nerves radiate pain. The starting point of pain can be a trapped nerve in the back of your head (occipital). These nerves tend to radiate behind the eye and down the neck and shoulder even though the problem really is a trapped or damaged nerve in the back of the head. The nerve can cause pain along the route and cause muscles to spasm along the way. Various sensory nerves are all over your scalp and radiate pain to different places including the face and forehead.
People with back pain often experience pain shooting down one of their legs, even though the problem is the back. The sciatic nerve becomes trapped or pinched in the back. The nerve radiates pain down the leg. Heart attacks are often felt in the arm or neck because the pain is referred. This is the same principle.
If a nerve block is injected at the point where the nerve is trapped it will stop the pain behind the eye and neck as well. Nerve blocks can help diagnose where the pain is pinched or trapped.
As far as I can tell, there are about 4 main options. (I've done them all!)
1) Hope that the nerve dies and stops transmitting pain totally or to some degree. (I have heard this happens but can find no statistics.)
2) Hope that the nerve becomes untrapped. (Physical therapy, massage or chiropractic might help)
3) Take medications to make it more difficult for the nerve to transmit pain or muscles to contract. (Oral medications, nerve blocks, Botox, heat, ice, ect.)
4) Surgically release the nerve.
To say the least, these headaches are complicated. My headache neurologist mentioned that these types of headaches can also trigger a migraine component and visa versa. This might explain the prolonged "train wrecks" people on this site describe.
Best Wishes,
Janet