Do you think I have something?

So my first body was a year ago and it was also his first time, and the second time was last christmas. I didn’t get any symptoms from either times and they didn’t have any open sores on their mouth or anything, but I got a canker sore in my mouth and I feel like I might have something. For the symptoms of STDs, I don’t have any. I can’t even go get checked, but tell me your opinion.