In 3 years i've been treated 4 times for bacterial vaginosis. why does it recur? is it possible there's a bigger problem?

Recurrent Vaginosis: Bacterial vaginosis is a very nonspecific diagnosis. When there is no yeast in the vagina and there is a purulent vaginal discharge a diagnosis of bacterial vaginosis can be made. There could be other reasons such as endometritis causing this purulence or a cervicitis. Ask your gyno for help. Get a second opinion. See your doctor instead of your np.