This may be a weird question..but help!

My boyfriend and I had sex about three or four days ago. We don't use condoms and he doesn't pull out, we've been together a year and nothing like this has happened. Ever since then my vagina has had this really bad smell. Almost sour. I've had yeast infections and I don't feel like I have one. I've tried just washing with water. Even a little summers eve. But it doesn't seem to be getting any better or worse. Any suggestions??