Bleeding for 2 weeks!

So long story short, in May I was told I have HPV and had to have a coloscopy done to check for cervical cancer. Abnormal cells were found but I was told it was find and to go back for a follow up in 6 months.
I've been on birth control since I was 16 and I'm 19 now but now I've been bleeding for going on 2 weeks. Most of it is a dark brown blood and I should be starting my period this Saturday. I called my doctor to make an appointment and his nurse talked to him and told me that he didn't think I needed to come in unless it got worse. I have had no cramping or anything like that, just the bleeding.
I have no idea what it could be!!