I am sorry to hear you are still suffering!! We are note medically trained here, we are all sufferers, so our help is limited to stating opinion based on our own experiences!!!
Have you seen a Neuro who is a Headache Specialist? If not I suggest that you do as he/she will understand headache much better than an ordinary Neuro!!! There are no specific tests for the different types of headaches but the MRI's and CT's are done to rule out the nasties, so as yours have come out clear I would say you have nothing to worry about!!!
Hang in there, take care
Co-Moderator of the Migraine/Headache Forum