I found this comprehensive article about some clinical studies. Read the bottom 4 paragraphs. There are a number of brands that sell the Petadolex extract. Just google Petadolex

Have you be checked to see if you have muscle spasming from your neck to behind your ears ? This is a common cause of headaches. Sleep quality also impacts headaches.

I have chronic headaches for about 6 months after 2 different concussions. I used acetaminophen with aspirin for the worst and ibuprofen for the less painful.