So confused!!

NiNi
I know I ovulated a week later than I was supposed to on July 7th, but I still had (what I thought was) my period July 13th. It was lighter than usual, but didn't think anything of it. But today July 15th there's no more bleeding, but I am having symptoms like breast pain and tenderness, stomachache and nausea, and crampy. 
Could I have mistaken my period for implantation bleeding??! I'm not even sure when I should test!