Bleeding after sex.??

Moriah

Sooo I had a period for 14 days straight!! 🙄 and it started right after having sex with my boyfriend. Then finally it stopped and I was super happy but about 3-4 days after it stopped I had sex with my boyfriend AND IM BLEEDING AGAIN! Not like spotting. It’s full blown bleeding. I have Nexplanon (the arm birth control) and I’m thinking maybe this has something to do with it. Help???? Is this normal???