Itching and burning

I woke up yesterday morning with a very itchy feeling down there and I tried ignoring it but it just kept getting worse. When I went to the bathroom and wiped, it started burning really badly and I found blood on the toilet paper. I know it's not period blood because my period isn't expected for another two weeks. I also have been having a lot more discharge than normal and it's thick, white and has a different smell than normal. I've looked down there with a mirror and nothing looks irritated or anything. I had unprotected sex about three weeks ago so is it possible that this is related to an infection or STD? Or is this something that should go away in a few days?