Metronidazole 500mg during the first trimester?

Ada
I just spend 6 hours at the ER yesterday due to heave bleeding they did a pelvic exam and it looked close as it should be and also an HCG test and it came back at 30k from last week that I was only 2404 but they did find a vaginal bacteria and this morning I was prescribe Metronidazole 500mg twice a day for 7 days. Now after reading a bunch of stuff  in Google and calling two different pharmacist I was told it was a class B pill and assumed safe in most cases but not usually during the first trimester. I honestly don't know what to do, having the bacteria is not good but I'm also concern about it being that I'm only 6 weeks pregnant. Had anyone taken it before and been fine?