You may have damage or compression of your occipital nerve, since the location and description of the pain are very symptomatic of occipital neuralgia. This pain usually responds well to SSRI-type (selective serotonin reuptake inhibitor) antidepressants and/or anti-seizure meds. Cymbalta, Lexapro, Elavil, Pamelor, Klonopin, Lyrica, Keppra, and Neurontin are often prescribed, either alone or in combinations.
Good luck!
sounds like the same thing I have been experienceing lately..i did some research and sounds like they are called 'ice pick headaches' .. i know what you feel.. they are very strange.. they usually happen to people with migranes... maybe check that out