One other thing: I was in a specialist neurology hospital a while back, and there was a guy in the bed next to me who suffered from terrible cluster headaches. He used to inject himself with morphine almost daily because they were so terrible.

He was started on a new drug (still not licensed for use in England, so he had to sign a disclaimer) called dihydroergotamine. (How I remembered that name I'll never know!) It's a pill that he has to take daily, and instead of treating the headaches when they showed up, it is actually meant to work in some way (I don't know how) to prevent them. He said it was brilliant, and that it had left him with far fewer cluster headaches, and when he did get them, they were far milder.

I don't know, but considering the report I got from the guy, it appears as though it's a good medication, so I thought you might want to look into it.