Antibiotics are NOT natural substances. Pennicilin was but they couldn't make any money because of that, so they developed the drugs to make the money off the patent.
The microscopic parasites ARE microscopic and don't give too much of a problem. Humaworm is good for them though. And I'm sure the DeWormer does a number on them also. Otherwise simply don't worry about them. Once the big critters are gone and the systems built up a bit anything microscopic will dissappear. I can hear the objections to that already. Yes, there are exceptions; malaria, lymes, etc.
It's NOT possible to be sick with a healthy liver. Life is as good as the liver. literally and personally.