Brownish Discharge 3-5 days after period ended

Patient: Had sex with my boyfriend on March 20th. We didn’t use a condom but he never ejaculated. I’ve also been on birth control pills for 5 years which I’m very religious at taking them. I got my period on March 28th and it lasted until April 1st. It seems pretty normal. Now for the last few days i’ve been checking my CM and it seems to be brownish in color. Should I be worried about this? Could this be pregnancy? or is it more than likely from my period?