Interesting input @frankbacon, I read a lot of good studies showed very promising medical use of cannabis. I didn't hear about study to use it treating headache yet.
I didn't get your point about emotional stress but i think it is a result to trigger, you are right about not addressing it as a symptom in medicine, a symptom means something that patient complain of.
Placebo effect is documented medical phenomena, actually some doctors use it, they give a Placebo pills (pill full of sugar) to certain patient.
Thanks for commenting
by the way nice picture my friend