Yeast infections after sex? Never happened before

A few months ago I got BV after having sex with my partner and now I have a yeast infection also after having sex with my partner? We both have had full panel STD testing, we’re only seeing each other, we both shower regularly, I don’t use any soaps down there (my ob said not too) I don’t even use tampons. I take probiotics and wear cotton underwear so idk why this is happening and idk what to do about it, does this happen to anybody else? I’ve heard using boric acid after sex can help prevent stuff like this but I’m scared to try it. I’ve talked to my OB and she said everything’s fine and that this just happens sometimes🤷🏻‍♀️

What do you guys do? What should I do?