Help!!

So I started seeing this new guy and it’s been 3 weeks since we started having sex. He would get really rough (which was hot) but I after I felt like I was chaffing. We fucked a few more times like that and now I have sores and I’m scared it’s an STD. But it could also be an allergic reaction because I started doing laundry at his house and I’m allergic to his laundry soap. I am going to the doctor tomorrow but can anyone tell me what it looks like.