Mine are set off by tiredness and sometimes stress.
I get flashing lights, pressure behind one eye, then (usually all of a sudden) nearly complete loss of vision, sometimes ringing in my ears, always numbness in my hands and feet, and vomiting about half of the time. It'll go from a mild headache to all of this within about 5 minutes. Its horrible. I've been getting them since I was 12, so 7 years. My brother is 14 and just started getting the intense headaches and vomiting.
I have to lay in a completely dark room until its gone.
Luckily I haven't gotten one when I've been alone with DD. There's no way I could take care of her.

Hope you feel better.