Cluster Headaches? I hope not, and I don't think so. I hope.
daikitsune suggested that my headache might be a cluster headache. After reading up on them, if that's what they are, I am one of the luckiest guys in the world. Typically, clusters are debilitating painful. Sufferers who have had a basis of comparison say they hurt worse than passing a kidney stone, and they constantly recur, typically right about the time REM sleep begins. So you get this horrible runaway cycle were sufferers will race off to where they can't be seen, and then "dance" and scream and bang their head and press on their eye due to the torturous pain, and they fear sleep.
My headaches match some of the symptoms, but not well. The constant nature of it has changed to episodic flairups, but I've not noticed any real time based pattern to them. I do get the "droopy eyelid", and the one-sided congestion, and I did have a very minor head injury on that side several years ago, similar to the pre-onset history reported by many "clusterheads". But if it is CH, it's rather idiosyncratic. It is the worst recurring headache I've ever had, but yet, it is so harmlessly mild compared to sickening misery of the typical CH syndrome, that I doubt that's what I have.
At least, I really really really really really hope that I don't.