Before you start combining Metronidazole with an herbal mixture, please consult your doctor. It is difficult to give an unambiguous answer on the basis of such a short description. If you are unable to consult your doctor, you can use the teleconsultation here:
https://www.gdziepolek.pl/telekonsultacja

Some herbs can affect the metabolism of drugs in the body, increasing or decreasing their effectiveness or the risk of side effects. It is important to know the composition of the herbal mixture and talk to your doctor about potential interactions.

Please remember that any modifications in the therapy, in the willingness to use a herbal mixture for parasites, should be introduced after consultation with the attending physician familiar with your health condition in detail.

The GdziePoLek.pl service also allows you to book a drug at a selected stationary pharmacy and collect it upon presentation of a prescription:

https://www.gdziepolek.pl/produkty/48758/metronidazol-polpharma-tabletki/apteki