ladies help!

I had sex with my boyfriend last Saturday and we have been ttc my period is or was 2 months late but we had sex and it hurt which is off cuz it never hurts! well next day I had light spotting and it lasted for 7 days well with my period it is really HEAVY and i have bad bad cramps well with the light spotting spotting it wasnt like my normal period and i had no cramps well now that my period ended 4 days ago,I'm having,real bad cramps any body else have this this happened?? also,I,never bleed after sex or any days after sex so I didn't know it was my period or implantion and cuz I'm having cramps after it ended threw me off