Anaerobyl reportedly contains the active ingredient Metronidazole, which is in a class of medications called nitroimidazole antimicrobials and works by stopping the growth of bacteria.

“Metronidazole is used to treat infections of the reproductive system, GI tract, skin, heart, bone, joint, lung, blood, nervous system, and other areas of the body. It is also used to treat certain STI's. Metronidazole is also used to treat bacterial vaginosis (an infection caused by too much of certain types of harmful bacteria in the vagina) in women."

[1] (Metronidazole) MedlinePlus

[2] Metronidazole is still the drug of choice for treatment of anaerobic infections

The U.S. FDA lists its typical side effects as possibly including nausea, dizziness, headache, non-allergic skin rash, and diarrhea.

For clarification, it may be best to ask your prescribing doctor if the pain you're experiencing could be associated with an underlying infection.

I hope this information helps!