I used to have bad, ongoing YI/BV problems. They did not seem to be bike-riding related.
I went through a few rounds of heavy-duty meds, even Diflucan. They didn't clear it all up. I also did some home remedies at the same time.
The remedy that I think helped me the most was the vinegar bath. I also put a few squirts of povidine-iodone solution in (antimicrobial). When mine was really bad I'd do the bath 2x day. Take a book, sit for 1/2 hr until water cools off.
I've been infection-free for a couple of years now. I also take Azo Yeast tablets as a preventative.
I am a bit particular about the chamois in my riding shorts. If it is too thick or stiff I find it irritating. I cannot wear PI shorts. My faves are older Hind and Insport shorts, they have very thin padding. I also like Blackbottoms shorts.
Do web search for making boric acid tabs also.
Specialized Ruby
Gunnar Sport
Salsa Vaya Ti
Novara Randonee x2
Motobecane Fantom CXX (Surly Crosscheck)
Jamis Dragon