I was diagnosed with endometrial polyp and given a bunch of antibiotic…

I was diagnosed with endometrial polyp and given a bunch of antibiotics. Among them were metronidazole, calcium chloride, ceftriaxone, and demafton. I'm on breastfeeding and warned my gynecologist about this. She said these antibiotics don't harm the baby. But online people say otherwise. Who took these antibiotics while breastfeeding? How did the child cope with it? Should I take antibiotics?