.....die off or herx reaction relates to toxins and bacteria released from the dead parasites, their eggs and their debri [biofilm] which has to be cleared from the system.
die off can cause headaches, foggyness, fatigue, weakness, aches and pains and must be flushed out by drinking fluids. taking those herbs and supplements that assist in clearing and cleansing the body of these toxins. If the die off is too severe than slow down the herbs and zapping to give time to disperse and start the treatments again.
I'm sure someone here will soon give you more advice