Stress and tension are a big trigger for me too, also cheese, wine (alcohol in general unfortunately!) and too much or too little sleep.
I got some co-enzyme Q10 recently which was suggested in another post: https://www.healingwell.com/community/default.aspx?f=31&m=145630
which has worked wonders (as a preventative)!!
I also get the numbness thing sometimes, usually in one arm, leg, or face. It's kinda scary. The first time it happened I was at school in a science lesson, and it scared the hell out of me!