Is It Normal To Have Intermittent Bleeding When On Menstruation?

Hi i had been on my period for 4 days it usually lasts for 6-7 days, i had sex with my partner on the 4th day was still menstruating at that time, we didnt use protection, straight after my period completley stopped and dissapeared for 2 and a half days then i had a slight bleed thisafternoon, now it has gone again??? Is that normal, and could i be pregnant?