So I wanted to mention the possibility that you have strept. I’ve had it dozens of times and had to get my tonsils removed. The problem with strept is the only treatment is with antibiotics. It will still survive the antibiotics and so what you need to do is address repleneshing your gut flora.
If you improve your digestion and improve your gut flora, this should kill most of the bad bugs.
Parasite testing will likely be inconclusive. We all have parasites, but at different levels…there is no way to avoid having them and there is no way to kill them off completely within the body.