Spotting??

So I'm supposed to be getting my period this Saturday and on Saturday night we had sex and there was blood... I assumed I was getting my period early because my cycle can be messed up but all the next day there wasn't any bleeding. We had sex again last night and there was a small amount of blood but nothing at all today. Could this be implantation bleeding or what could be going on?

Saturday and Sunday I woke up with my entire body aching but its been better today. My breasts are a little tender but only to touch. Ovia says not to test until saturday...

Any ideas on the blood?!?!