Will an ovarian cyst cause a foul smelling discharge?

No: The ovaries are not connected to the uterus or vagina. An ovarian cyst is a separate issue from malodorous vaginal discharge. This is a sign of infection, such as bv, and should be evaluated and treated. This is especially important if you are having pelvic pain that you are assuming is an ovarian cyst, but might actually be a sign of a pelvic infection!