The International Headache Society (IHS) International Classification of Headache Disorders 3rd edition (ICHD-3). Specific diagnostic criteria, details, and information on all headache and facial pain disorders can be found here.
https://www.ichd-3.org
American Migraine Foundation (AMF)
http://www.americanmigrainefoundation.org/
National Headache Foundation (NHF)
http://www.headaches.org/
American Headache Society (AHS)
https://americanheadachesociety.org
International Headache Society (IHS)
http://www.ihs-headache.org/
National Institute of Neurological Disorders and Stroke (NINDS)
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Hope-Through-Research/Headache-Hope-Through-Research
United Council for Neurologic Subspecialties (UCNS) List of Headache Specialists by State:
https://www.ucns.org/globals/axon/assets/10300.pdf
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.
https://www.botoxchronicmigraine.com/find-botox-specialist