Exercise can mobilize mercury...though it shouldn't do much more than make you feel not so good for a day or two. I personally do run every once in a while but find long walks much better, and I just got 10 fillings replaced about a month ago.

Don't overdo it, you may feel good one morning again soon and think going for a run is a good idea, but then afterwards you may feel a bit dizzy and trembly and a little wierd the rest of the day and possibly the next.