I've been a lurker here for a while but your post had me signing up to respond
My experience with Cluster Headaches is what actually first showed me - empirically - that they are MBS related. I learned this long before ever hearing about TMS, Dr Sarno etc. so in a sense am "grateful" for allowing me to understand empirically how MBS operates (and thus hopefully for its application elsewhere)
I had my first CH episode at 22, and pretty much would have an episode (4-8 weeks) every year or two all the way into my mid 40s. I kinda noticed that the episodes would come after a period of high anxiety or stress or major life event. Of course any mention of the CH forums of this being anxiety-related was usually shut down. But I had my suspicions. Then, about 10 years ago, a year of so after my last episode, for some reason I decided to check out a CH forum (FB page actually). I noticed that JUST LOOKING AT THE PAGE I started getting that little "twinge" and watering eye (CHers know what I mean). I left the page and the twinge/shadow didnt actually progress into a full blown attack.
The same sort of thing has happened since (and may happen now that Im here writing this lol) but every time its just been a twinge or shadow as they are called. No real pain, relatively. In fact I've had shadows for a couple weeks but so far....no attacks for over 10 years now.
Of course, I ended up having other MBS symptoms (CFS, other pain and sensation) that I attribute to anxiety, but my point is that experience I had sorta proved to me first hand that they are MBS related. I mean, they fit the category....medically unexplained, show up randomly, still no actual medical explanation of what "causes" them.
But more than anything, it was that experience I had, directly, that I think just "convinced" my brain of what I had been suspecting. Then I guess my brain just decided there is nothing more to see here...and looked for something else to pre-occupy itself with.
I know its 5 years since your post but hopefully my experience helps you or others. If you are still experiencing CH, first of all I am sympathetic and sorry to know that. But I just wanted to say that YES in my opinion I am sure they are MBS, for what that is worth.
Anyway, I wish sometimes my brain would see my other symptoms like fatigue or tension/pain as MBS as it seems to have done for CH. I'm also hopefully that MBS will look more closely at CH, since if we are talking about "pain"...well, CH really sucks (for those who have done "the dance" more times then they care to remember).
Wishing everyone the best...