Yesterday, while I was at a party I felt a small pain from the sides of my tongue whenever I touched it with my teeth. I simply ignored it, but today I still felt it and then checked it in the mirror. I freaked out thinking that I had an STI due to the fact that my girlfriend and I had unprotected 69 almost a month ago (we were clueless about the risks), and the symptoms are showing. Although, upon futher research I found that it might be canker sores from eating so much junk food and not brushing my teeth much. So which is it?