Zipper rubbed on outside of vagina

A few days ago I had sex and my partner didn’t take his pants off. He unzipped his jeans and pulled himself out. When I was on top of him I knew it was uncomfortable but I didn’t really think about it. Now 3 or 4 days later I have an extremely sensitive sore where his zipper rubbed/stabbed me while I was on top of him. Does anyone have any insight to help it go away?