I'm 17 and have been on Yasmin for over a year now to treat PCOS as well as prevent pregnancy. I'm just now experiencing a lot of dark spotting with some odor the week before my period even thought I've taken the pill on time every day. The longest this spotting has lasted was almost a whole month back in January, but I've been okay since, until now. Why is this happening, and will switching pills or going off of them interfere with my PCOS treatment?