Worried 😳

The weekend of September 27th - 29th I had unprotected sex with my s/o. I’m on birth control & have been for almost 2 years now but i forgot a pill or two so i went and bought a plan b pill (take action) on September 30th. I’ve since then been taking my pill regularly and not forgetting it. My period is due to come this sunday or monday & on tuesday i had a discharge that was really light brown which lasted for a day

and my boobs have been sore and i’ve been having light cramps. I’m not sure if it’s the pill that’s messing with my period?? it’s not my first time taking a pill like that either.. what’re your guys thoughts??