I'm not sure what is causing them...
Last summer they came on when I was at work at the barn teaching lessons- I figured it had to do with something I was allergic to. Went to an allergist and came back negative to all of the tests...
The last one I had came close to my menstraul cycle, so I am guessing it was hormone related, but yesterday I have no idea. Still a good week, week and a half out from that time of the month. We did just have a nasty storm come through here so maybe it is weather related... who knows.

I did just get an MRI done of my neck and shoulder and it turns out I have 3 discs in my neck that don't have any fluid in them, the orthopedic told me that could be causing some of the problems. I really have no idea, maybe I should go to my GP and see what he thinks.