My last encounter was over a month ago. Haven't been sexually actively since then. Period started this week and I left my tampon in too long but when I took it out, I noticed fbis sore. It's painful and a little swollen but I have no vaginal discharge and I'm not itching. It doesn't burn when I pee and I haven't had blisters or bumps. I don't feel sick and my throats isn't sore. No pus or blood has come out of the sore (even when I squeeze it). Is this herpes/ another STD?