Die off, healing crisis, herxheimer reaction...all of these names refer to what happens when the body is killing bad things that has made it sick.
When then body begins to host a parasite, whether it is a virus, bacteria, mold, tapeworm, fluke or round worm...it has to go through changes to host the parasite AND to keep you alive.
As the body changes, it will exhibit symptoms...signs that "something" is happening. Suppression of symptoms does NOT mean that the root cause of the problem is gone, it only means that the body has adjusted itself to the problem.
When you kill the root cause of the problem and begin to remove toxins...the original symptoms will return for a short while. This is a healing crisis.