Keep having vaginal discharge. Std test, pe, ps, and ultrasound. Nothing shows up. Recent pelvic & pap was 2/25/13, clear. Had period, now discharging?

May be normal. Discharge is physiologic it's only when it changes from what is normal for you that it may indicate a problem. Many young women start on birth control pills early and are on them for many years. While on the pill discharge is much different then when not on the pill. If all work up is negative and no symptoms it may be normal. Don't forget to inform your doc about any drugs your on.