Hi. I'm 18 and started taking birth control pills (ortho-tricyclin lo) about a month ago. I have been really good about taking pills regularly however i missed one pill in the third week. a few days after missing the pill i began to bleed but not knowing i was supposed to start a new pack i got to the sugar pills before speaking to a health care professional who said i needed to start a new pack. i started taking the new pills six days ago and am still bleeding. although the bleeding is fairly light it is inconvienient. what causes this and how can i stop it?