What Causes Foul Smelling Vaginal Discharge?

Hi am a 28yr old female and have been having a foul smelling vaginal discharge. this embarrasses me since it permeates through my clothes and i end up having to wear strong perfumes or panty liners. i havent had sex in three years so i dont think its an sti. this started after i moved to a very hot environment. it is usually between periods and there are times the discharge is too much. I havent had treatment for it. Kindly help