I want to play a bit with this idea of "worst."
In one sense, my "worst" trigger is the one I have not yet identified. I am relatively new to migraine, and identifying triggers can be very challenging, because it is so difficult to isolate variables. I have tried keeping a headache journal, but I have not managed to discern patterns. Add to this difficulty the fact that I have read and heard differing opinions about how much time can elapse between exposure to a trigger and its effect.
(Side note: I find the notion of "stacking triggers"--where something might not trigger a migraine in itself, but if, say, you are run down, or have not been eating well or otherwise taking care of yourself, or if various foods or whatever combine together, then WHAMMO.)
I suspect I still deal with a number of unknown triggers. In the realm of food, I have tried eliminating a number of things--alcohol, caffeine, gluten, dairy protein, egg protein. I have not yet tried the "elimination diet"--where you rule out almost everything and then add things back one at a time--but I may try that soon. But fundamentally, I have been unable to see a correlation between food and migraine.
(Another side note: one pattern I have recognized is that I seem to have almost seasonal phases--periods of pretty much daily migraine and then periods where even my usual triggers do not seem to matter. I have a hard time understanding the reasons for these phases: they do not seem to involve allergies, but is it weather? sunshine? patterns of work and play? Help me Obi-Wan; you are my only hope.)
Insufficient sleep is very bad trigger, in part because I cannot really control it. I do all the "sleep hygiene" things you are supposed to do, but I still often wake up around 3 a.m., my mind racing. The worst thing about insufficient sleep is that I sometimes get myself even more worked up, thinking about how the sleep I am missing might enrage the migraine beast. Fortunately, I have learned a number of strategies for coping with this problem--meditation, mindfulness exercises, "wise mind" exercises, etc. They help. Sometimes.
Other triggers that I think I have identified come with problems, in that I cannot really eliminate or avoid them. I seem to be sensitive to fluorescent light, and that is somewhat manageable in that I can avoid fluorescent bulbs in my house and keep the overhead lights off in my office. (I cannot, of course, avoid the fluorescents in the hallways, classrooms, and meeting rooms at work.) This sensitivity may also extend to my computer monitor, so it might be that extended computer time makes things worse. I cannot avoid the computer at work, of course, but I try to push away from it when I can and dim my monitor.
And as for many other migraineurs, weather seems to be a trigger, but I am not sure whether I can tell what the specific factor is. I think that fluctuation in barometric pressure is a trigger--most of the time. Humidity may be an issue. But then sometimes I feel worse on days when the weather would seem to be my friend.
Then there is driving, though again I am not certain whether driving itself is the problem, or whether it involves things that are triggering. (Many people agree now, for instance, that stress in itself may not be a trigger, but that situations of stress often involve other behaviors which may be triggers--such as eating poorly or irregularly, losing sleep, not drinking enough water, etc.) So is it the motion of the car? The position of my neck in the car? The fluctuation in atmospheric conditions that can come with going outside from air conditioning inside?
All in all, though, my "worst" trigger, in that it is my saddest trigger, is exercise. Again, not always, but frequently enough that I see a strong pattern--and indeed it was with swimming that I first started feeling the effects of migraine. I say that this one is the worst not just because everything we read says that exercise is good for you and should be a part of everyone's regular routine. For me it is the worst because I. Love. Swimming. Love it. For about twenty years now, it has been my favorite mode of stress release. I love being in the water. I am a really good swimmer, so swimming well makes me feel powerful, capable, agile, fast. Old readers of this blog will know this to be true, because over and over again I would write about swimming. In fact, the car wreck that may have been the initiator of my migraine dealings killed my plans for a swim meet.
I hate wondering, before practice, whether I should go or not, whether this practice will be one that brings horrible pain. I hate wondering, during practice, whether I need to dial things back so that I can stay under the triggering threshold (which is, in itself, variable). I hate having to get out of practice early, because I can tell that things are getting bad. I hate wondering, after I decided not to go to practice, whether it would have been OK. I hate having this thing that I love so much, so tainted.
So I try other kinds of exercise, too, and sometimes they work better than swimming. I go for walks, and it is great to be outdoors, but I miss the drive and intensity of the pool. I ride my bike, but that does not bring the zen feeling of the water.
And frankly, as much as I can without risking being unable to go to work or something like that, I swim.