Can "yeast" infection be sexually tramsmitted?

I've heard that you can transmit things that are like yeast infections by sex. It won't be yeast yeast, but something that has similar symptoms, sometimes worse. I know a gyno can give cream to a couple, so the man can apply it as well. I mean, transmitting fungus seems pretty reasonable, but I'm wondering if anyone's heard of it. I don't know what it's called and most doctors seem kind of ininformed about it. The only thing I know is that I never had yeast infections until I started having sex - I was on the pill, so it was without a condom. Then I decided to use condoms, and was problem free for a while. When I was in a committed relationships with someone that has never been with anyone else, I was fine also. Same when I have no sex. About a month ago I had condom-less sex with someone who was much, much older than me, and I've been having horrible symptoms since. I thought maybe older men have more fungus on them or something... Does anyone have any idea?