Metronidazole and birth control pills

Long story short I was tested for BV on Friday, and I tested positive for BV, I began my metronidazole pills Tuesday morning. But I’ve been having some weird spotting since Sunday. I last had unprotected sex on Saturday and my partner did ejaculate inside me. I have been taking my birth control pills as normal but noticed my app said I ovulated Wednesday. So I was just wondering does this certain antibiotic make bc ineffective?