Implantation bleeding

Im really confused and need some help. My period ended the 10th of july, and then i started bleeding again the 22nd of july. but this bleeding was different, it was heavy and ran down my legs, it was just alot of blood but it wasnt the same colour as period blood, it was brownish and then slight pink with no clots. this bleeding only lasted like for  couple of seconds and then stopped within one day.i have a 30-31 day cycle.My fiance and i had sex a day before my period ended,6 days after my period ended and on the 22nd of july after i stopped bleeding.Is this implantation bleeding or sumn else? My period isnt due till the 3rd of august.