I gave my boyfriend head & right after I noticed a cold sore at the inner right corner of my lip, is this bad?

I get cold sores here and there and I never give him head when I do. Today after finishing I noticed a cold sore after on my lip, I'm so scared that he's going to an STD..... but there were many times when I did have one and he's kissed me and then he'd give me head, and I'm fine.. but I don't know! Please help! :(