What Does Pasty, Purplish Vaginal Bleeding While On Loestrin Suggest?

First started where I thought I had peed myself, looked at my underwear and it was bright red. The longer the bleeding went on, it became a thick pasty purplish brown color. Took a pregnancy test came back negative. I am currently taking loestrin 24 fe and have been for around 5 years. Am I pregnant??