What Causes Smelly White Vaginal Discharge?

hi i am 17 years old and i am sexually active in the last couple months i been getting a white discharge and its almost daily sometimes is a lot it has a smell but doesn't stink really bad i went to the doctor already and they told me that it was probably a yeast infection and they gave me medicine for it but it didn't go away i have no idea what it could be can you help me?