Thanks Waves... I haven't had any of those, because the pain/headache clinic doc I saw didn't feel they were needed. Obviously I need to find another pain clinic!

I can't think of any health incident/accident that could have caused the trigger to worsen. I did have a uterine fibroid, but it arose slowly and has since been removed (complete hysterectomy last fall didn't make any difference at all in the migraine problems, but that's not why I had it).