Everytime my boyfriend gives me oral sex i get bv. we never use a dental dam or any protection when i receive oral from him.is this causing my bv?

Recurrent BV: It's possible your BV is related to receiving oral sex, but not necessarily. It would be helpful to know the frequency of the oral sex exposures and whether you're sure BV is entirely gone between those episodes. Have you been properly treated (metronidazole orally)? Many women have borderline BV, with fluctuating symptoms. Metrogel or boric acid capsules may help prevent it. Discuss w/ doctor.

Maybe: Since the BV is occurring every time that oral sex is done to you, then it is likely that his oral bacteria are invading the vaginal space and changing the normal vaginal flora.(content). If you are using douches or harsh soaps in the area stop them now. Consider the use of Listerine mouthwash by him prior to engaging in oral sex. The mouth contains far more disease type bacteria than the vagina.