The International Headache Society (IHS) International Classification of Headache Disorders 3rd edition (ICHD-3). More specific diagnostic criteria, details, and information about each type of headache and facial pain disorder can found here.
American Migraine Foundation (AMF)
National Headache Foundation (NHF)
American Headache Society (AHS)
International Headache Society (IHS)
National Institute of Neurological Disorders and Stroke (NINDS)
United Council for Neurologic Subspecialties (UCNS) List of Headache Specialists by State:
This is a list of specialists who treat chronic migraine with Botox, although it is not an all-inclusive list. However, it can also help with simply finding a headache specialist closest to your zip code to further evaluate your headache or facial pain disorder.