What Does Bleeding After Having Sex Suggest?

Gooday sir/ma, had sex wid anoder guy buT mistakenly he release inside of me .when I was cleaning up i saw blood on d tissue, I took salt and water imedtly then after an hour 30minute i took postinor 1. What baffles me most is the blood I saw. What is the cause and what's the solution and steps I need to take? Thank you and hope to get a reply soon.