Bacterial vaginitis shares symptoms with a yeast infection: it causes inflammation and itching of the vagina as well as increased discharge with a fishy scent. It is caused by a surge of bad bacteria in the system. There is always bacteria within the vagina, but there's USUALLY more good than bad. Sex with multiple partners, smoking, antibiotic use, and douching can put you at risk of this infection, which throws your bacteria out of balance. Luckily, this problem usually clears itself up within a few days. If you're pregnant, see your doctor immediately -there IS risk of a miscarriage, early delivery and other complications.