Implantation or period WARNING GRAPHIC

I had unprotected sex on the 14th of June . It was really rough and he was hitting my cervix, later that night I went to pee and I had bled alittle, which has never happened to me before. My period was due today , June 20th and I started bleeding but it wasn't normal, it's lighter than normal and also had alittle chunk of gooey discharge. I don't know what it could be . ALSO I AM ON BIRTH CONTROL