I Had Been Using Tampons For 15 Years Then Switched

I had been using tampons for 15 years then switched to menstrual cups about 4 years ago. Everything was great until my previous cycle. I started becoming irritated from the cup my period and went to the gyn. He cultured and said it looked like BV, but I don't think that's what it was. I started the antibiotic and took a Diflucan pill a few days after that to prevent a yeast infection. Finally healed and then got my period again a few weeks later. Same thing happened, so I used pads only (no tampons or cup) and now I am fine. What can this be?