Humaworm, like any other medicine, contains chemicals. Natural herbal chemicals. The amount of chemicals in the formula can only take care of a certain amount of parasites and toxins.
When hand washing dishes, you only need a drop or two of dishwashing liquid to clean glasses whereas you need much more dishwashing liquid to clean greasy pots and pans.
This is the same with parasite cleansing. Light infections only need one round of Humaworm (like the glasses) whereas heavier infections need more rounds of Humaworm (like the pots and pans).
If there were a magic pill to kill all parasites at the same time, the toxin overload would kill the parasite host. This is why the 30 day treatment is best.
What you are seeing could be "leftover" parasites or it could be mucous.