Hello all,
   I'm pretty sure I've had this problem my whole life. As a youngster, I didn't have the intense pain, but every year, like clock work I would have "allergies" that only affected the left eye, with lots mucus draining from the left nostril, tearing etc.
   While working as a nurse, I would have episodes that curiously were relieved by about 4 teaspoons of liquid Motrin. After a few years, I changed careers, and beat my liquid Motrin problem (lol). Not being diagnosed, and with the episodes still tolerable, I started a business, operating heavy equipment.
    With this new responsibility came a time shift in those episodes, that seemed to have brought along a fiendish cohort. A new definition of torment I'd never before endured. Initially, dayquil gelcaps, if taken soon enough, would stop the episode. But if not taken soon enough.....frantic expeditious trip home, which was sometimes a frightening trip, try to drive, and cover one eye, and scream at all of the innocents who just happen to be on the road.
   One day, it was unbearable, nothing worked, Extra strength Tylenol along with dayquil gelcaps, Tylenol 3, maybe excedrin and anything else in the drug cabinet. Tried lying down, standing up, lights on, lights off, running water, hands under running water, head under running water, standing on head in the dark with water running....no relief.
  My wife drove me to the ER where I was introduced to ergotamine, and the Dx, "you have Cluster Headaches".
  Since then, Imitrex (self injects) became a constant companion. It works, in 7 minutes, I was back to work. Then 9/11, I got deployed overseas, hmmm, no headaches the whole 18 months, maybe they're gone...... uh, no, merry Christmas, from 24 December 2004 to 5 January 2005, 18 episodes, which of course exceeded the usefulness of the Imitrex, not to mention a sore arm.
  The MD was more worried about my blood pressure and put me on Verapamil. I have taken it religiously for 7 years, without a recurrence of a CH........until now, currently in my ambiguous onset phase. The intensity of pain, once forgotten, now lurking behind my left eye....once more.

How much verapamil? I only ask, becuase way back in the beginning of these things for me, 240mg/day was the standard dose and coupled with ergotamine, seemed to help. Although I think I just went out of cycle, like you. Now 35 years late, I am chronic, and my dose of 640mg/day seems to be useful. You may have some room to play with in your dose levels if your doc wants to try going up. And for the record, O2 is the best! Blessings. lance