A) if you have any other symptoms on yourself you might want to see a doctor. (Are you itchy, do your underwear also smell a little, is your discharge a different color, ask your boyfriend to be completely honest and tell you if he's noticed a little smell, any cramps out of the usual etc).

B) your cup might be helped by a little hydrogen peroxide. Check what your cup is made of to make sure it won't be damaged by one hydrogen peroxide wash.

C) check where and how you store your cup between cycles. Make sure it's a breathable place and not something that is airtight. Even after it has dried completely you want your cup to to be in a well ventilated storage place. So if you put it in a cloth bag, where did you put that cloth bag afterwards?

D) your cup might be old or poor quality. When did you get it? Apparently they only last 10 years if made of silicone. I'm not sure about the other materials they can be made of like tpe and rubber. Or if it came from a place that doesnt have consistent quality control you might just be unlucky to have a dud of a cup.

Anyway, those are the only things I can think of. Hopefully this and the other comments in this thread are helpful to you.