herpes?

So Ive only been sleeping with one guy over the course of 6 months since my ex. We slept together recently and he had a cold sore, he didnt perform oral or anything like that, but we did end up swapping salvia and kissing even though I went into it trying not too. so two days after the sex I notice this rash pimple like break out thats equally itchy/sore on my buttcheeks. does this look like herpes? honestly give me any opinion/knowledge no matter how brutal. also he finished where the rash is so maybes thats related too. im so upset