Julia, I'm so sorry to read about what your husband is going through, and you with him. I'm not sure how they're related chemically, but my thought is that amitryptaline works differently from what I've been prescribed for cluster headaches - namely Sumatriptan. It's a migraine drug and really does the job. I call it the giant killer. You might ask about it.

For clusters at least (and this may not apply at all to your husband's situation, but I figure it can't hurt to ask) breathing pure oxygen at a high flow rate for 10-15 minutes also works very well. You'd have to get a rebreather mask though. A nasal cannula will not give him enough to do the trick. Again, just a suggestion.

Please keep us posted.