Andrew, you are right to seriously consider busting, and THMH has given you what you need to know: read the numbered files in the Files section and follow the process he has described.
If you have not done the "Vitamin D3" regimen you should start it. It has made a very big difference for many, many people. You can also read about that in the Files section. (I realize that people in your situation are inclined to eventually give up on treatments, and surely you might wonder how some vitamins will help you when powerful medicines have not helped. But many people in that very situation have achieved very good results with the D3 regimen. You have to follow it to the letter.
We find often that when people say they have "tried everything," they have missed some core elements, most particularly oxygen. Have you used oxygen? If so, how was it delivered? Because often people who did not get relief from oxygen were using ineffective delivery systems -- the regulator did not provide a high-enough flow rate; the mask was shoddy or used wrong; the O2 came from a concentrator, not from a tank/cylinder/cannister. No matter what success you have with busting and D3, effective oxygen can be a life-changer. If you have actually used everything pharmaceutical that typically helps with CH (I would include sumatriptan/Imigran, corticosteroids, and verapamil at the top of that list) and none of it helps you, and not even ketamine helps you, I have to say that I would also test a different diagnosis, such as paroxysmal hemicrania or hemicrania continua. Those things look a lot like cluster headaches -- but they are effectively treated with a single medication, indomethacin. So if indomethacin is not on the list of things you have tried, it would be worth a shot.