Okay, so I've done some pretty dumb stuff sexually since my teens, and I had BV for a while and discovered the trick of douching with diluted hydrogen peroxide. So the symptoms of BV would go away, but every month after my period ended, I would have to repeat the process because the fishy smell would come back. I thought it was because the high pH of menstrual blood was encouraging bacterial growth. But 2-3 weeks ago I went to the ER for a bad UTI that was accompanied by bad BV, and the doctor game me Cipro for the UTI and a 2g dose of Flagyl for the BV. I'd never taken Flagyl before, but it made the BV go away immediately. Then my period came and went, but no fishy smell followed it. So I'm starting to wonder: was the recurring BV actually caused by my period because it was my uterine lining that was infected all along, and it was re-infecting my vaginal canal when it shed every month? Have I had PID all these years? If so, did the Flagyl cure it?