I have heard that happens often, there are so many parasite
corpses the body has to deal with. It's like any cleanse I guess, the drain gets unplugged and all of a sudden the body has lots of stuff to get rid of.
I'm zapping steadily now on a daily basis for the first time (I've zapped before, just not several days in a row like this), and I get some abdominal cramps and faintness, but no loose stools so far. Possibly because I been drinking carob, which seems to stop diarrhea really well.
If enough of this goes on that you lose your intestinal bacteria, be sure to take some yogurt, kombucha, or other probiotic. Also, keep hydrated. Good luck!