Suggest Remedy For Irregular Menstruation

i started my period on may 4th, it lasted for 3 days and then it stopped. then i had unprotected sex and took plan b.... 4 or 5 days later, i had a 5 or 6 day long period again. then, i decided to start birth control when the second period in may stopped. .. now i've been taking birth control for a week and a half and i'm having brownish red discharge kind of period again stuff.