STD help

I have been with more men than I probably should have but I've always been safe and I've always been clean. Recently I've started to feel weird down there, off and on. It will burn when I pee, itch on the outside, and something doesn't feel right on the inside. I've had yeast infections and UTIs and I can't tell if this is the same or something different. I also don't have a way to get tested for STDs. What do you think it could be?