I have been having headaches for over 5 months

I have been having headaches for over 5 months. I have never had migraines before, but doctors are saying they are migraines. MRI and CAT scans have come out okay. What would cause these sudden and prolonged headaches? Will they ever stop? Migraine medicines do little, or nothing to help. The headaches seem to intensify with light, sound and very shortly after eating. I have tried glasses, chiropractor and neurologists, all to no avail. Is there anything else I can do to stop having these headaches that came out of nowhere and will not quit?