Period or implantation bleeding?

My boyfriend and I had sex July 20th and the noticed a few red after we were finished the next day I got my period which was a week early and super heavy. It was two days of heavy period and than light and now today July 24 I have little to nothing. And have stomach camps that started yesterday the 23. Not sure what to make of this I have now been off the depo shot for a year after being on it for 5 years.