This is going to sound really weird but I'm so concerned. I gave my boyfriend of 2 years oral. He's only ever had one other girlfriend and he's never had sex without a condom. After I gave him oral I mouthwashed. I then went home and I later that day kissed my little brother on the lips. Days later he has like a cold sore or something in his mouth. Could this be an STD? I did not have any sore in my mouth when I kissed him. Many thanks