When I was in my early teens I developed migraines. We couldn't figure out why and I would get them around once per month. Then my chiropractor figured out that they always happened after a stressful event (eg, fight with parents, grandmother dying etc). After that I only have the occasional one, 1 or 2 a year, but these don't seem to be linked to stressful events, just appear to be random.
My partner used to get really bad migraines and used to vomit whenever he ate chocoalte - he doesn't like chocolate much these days, but can eat it.
I don't think they quite know what causes them and they can have differnt reasons in different people, but migraines usually have some kind of visual disturbance (i described it as pixellation in my peripheral vision).
There was nothing I could do to stop mine, just have a cup of tea (seemed to work a bit, and apparently caffeine can help somehow) and go to sleep). Apparently sucking on ice can also help as it cools the blood flow to the brain.
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"