What Causes Abnormal And Excessive Vaginal Discharge?

I m experiencing some abnormal vaginal discharge. I had gone in to get a pap smear, and was treated for a yeast infection. I am currently still experiencing discharge (a lot more than normal, white, sometimes with an odor, and cottage cheese-like). I was tested for STD s too, and all tests came back negative. I m wondering what I should do next?