Helppp!! I’m freaking out

Has anyone had bacterial vaginosis since they been pregnant ... I’m 20 weeks and I never had it until I got pregnant I talked to my doctor and she said it was very common in pregnant women but she gave me a prescription and it went away about 2 days now it’s back and all the pills are gone (she tested me for std’s and they all came back negative ) anyone have tips on how to get rid of it ?