Herpes

So I've been dating this guy for about two months. During this time I've given him a few blow jobs and everything has been fine. I gave him a blow job tonight and immidiately after I was finished, I felt a sore forming in the corner of my mouth. It looks like a fat, puffy cold sore. He says he's clean and plans to get tested this week, for my reassurance. But I'm freaking out. Do I age oral herpes?? Has this ever happened to anyone before! Please help!!