What Causes Milky White Vaginal Discharge?

Hai Doctor, am 23 years old, i gad my lats period on 8th June, and yet now i hadnt got my period after that. But for the last 2 weeks their is milky discharge from my vagina.. I took pregnancy test but it was negative... As I was suffering from discomfortness in body i met a doctor and she suggested susuten 100.. can you please tel me what may be the reason for this vaginal discharge??? Am i pregnant??/