I use a cup everyday for what I've considered heavy discharge for a long time. I was not using cups at my last annual exam, nor had had any sexual partner for over a year. After last year's exam it was determined I had an "abnormal" pap smear, but it was probably okay. So this year I go in, and as per usual, she asks if I had abnornal bleeding, pain, discharge...yada-yada. I have always considered my heavy discharge normal, as it seems to have been that way since aldolecence, so I say no. After the exam the doctor went to look at one of the slides under the microscope. She came back in and said I have Bacterial Vaginosis, and that is why I have such heavy discharge, and what caused my last abnormal pap. She said it was common for those with this problem to complain of always having to wear a pantyliner (or my case a cup) because it's so heavy, and prescribed an antibiotic. But what I also found interesting is I don't fit any of the suspected risks. So if someone else has been going through the same thing, ask at your next pap. Even if you don't fit the causes!
After finishing off all the antibiotics, I sure enough ended up with a yeast infection. The first I've ever had in my life. :( Even worse, it was the guy I was having sex with that informed me afterwards of my condition. Also, after he had his mouth down there even. :((