I have spoken to several nutritional experts on this matter in the past. One felt the same as you. Another made a very constructive comment to me and I will never forget it when using the zapper.
All living organisms decay when they die. If the elimination system is not kept working properly (herbal laxatives, colonics, etc.) you could create more problems. This is imperative if one has a CHRONIC illness.
I came to a personal conclusion that is why Hulda had people zapping daily, sometimes more than once for long periods of time (until their systems had rid itself of the huge amounts of dead parasites.
I have a tendency not to read a book from front to back, I skip around alot and then pickup what I skipped.
My 4 year old daughter was grinding her teeth at night, which is a sign of parasites. I am unable to get her to take pills. So I decided to zap her. My father had already been doing this to himself so I felt confident. I only zapped her once. She woke up the next morning with a runny nose and sore throat. That morning I finished reading the part that said NEVER do just one zapping as is is possible to induce a cold. I immediately zapped my daughter the full 3 times. All cold symptoms left her right away.
Perhaps you were aware of such an important factor, and then again maybe this can shed some light on what happened.
Thomas and Ed were absolutely correct in saying it has to be used properly. And perhaps it is not for everyone as in your case.
In the spirit of well being,