Hi, Welcome to HCM, Vaginal Discharge with bad odor, usually indicates Infection in Vagina. iThe most common cause is bacterial vaginosis. Though there are many more causes for it like vaginitis, STD s like Chlamydia,genital warts, Gonorrhea, cervical cancer, Vaginal cancer, Polyps etc. I do not think that B Complex is the cause of smelly vaginal discharge, though if you have taken some Antibiotics also, it can cause Bacterial vaginosis. I would suggest that you go to see a gynecologist, who can do vaginal examination to confirm the diagnosis, and give you proper Treatment.