Breakthrough Bleeding 🤮

I just started taking a birth control pill, the day my period started 12/15/19 as my doctor said and my period ended on 12/23/19 and I’m experiencing a lot of dark brown discharge and it’s gross and I want it to stop because I’m trying to have sex with my girlfriend this weekend and it’s super gross, help!! The birth control type is Microgestin 1.5/30