Hi, and thanks for your medical question on eHealth forum

It is very difficult to diagnose the cause of your headache on net. However there are various possibilities that you can look into.

The symptoms that you have enumerated point towards spinal nerve compression at the cervical vertebral level. Sleeping in wrong posture, overuse of computers, neck sprain as in a jerk or car accident can all cause stiff neck.

High blood pressure is another possibility. Refractive errors and eye strain also cause headaches. Poor sleep pattern is another cause. Stress and tension can cause tension headaches.

Well, migraine, tension headaches, cluster headaches etc should all be looked into. However there are two other possibilities that you should explore.
One is dental ache as in an exposed root canal. This causes shooting unbearable pain radiating to head, neck, shoulder, ear, everywhere in the head and neck region I would say.A visit to your dentist is a must and should be the first step.

The second possibility is an internal ear pain. Again it is the same as dental pain. This appears to be ruled out in your case. However it would be good to seek another opinion.

The third possibility is brain tumor. You would need to consult a neurologist. However I think it is unlikely as you do not have any other neurological symptom. But you never know. Some tumors present first with a headache only.

The clue to right treatment is right diagnosis of the headache. Hope this helps. Take care!