STI, ph balance

So I haven’t had sex in a month my partner and I wear condoms we do have oral sex. My period comes on next week but there has been this bad odor coming from my vagina today and I don’t know what it is I want to say is a STI But it’s no itching involved I wear condoms with him so I don’t know what it could be.. help please, any over-the-counter drugs I can use? Or a certain type of yogurt that will help me?