sores

So I had unprotected sex on 09/24/16 my bf and I didn't get to finish. So I decided to take a plan b pill because I had unprotected sex and I was scared. I'm 17 btw and just yesterday I saw a sore on either my cervix, or vuvula. I don't know where exactly. It has I think white or yellow pus on top of the sore. It doesn't hurt at all, it just itches some times. Anyone know what it is? because I'm currently freaking out right now. Is it related to having unprotected sex?