What should I do???

So I had some bleeding yesterday (and then later what looked like tissue loss) that was a little more than spotting. So I called my doc and she said just put my feet up and call her office the next a.m. for an appt. Then later that night she had her exchange service call me and tell me to go to the ER last night. Ugh! I was so exhausted that I just wanted to go to bed. So we went to the ER and I was expecting the worst. Thankfully, the baby looked good on the u/s and the heart rate looked good (150s to 160s). Also the exam showed that my cervix is closed. So that was all a relief!

There was bacteria detected in my urine and they gave me an antibiotic for a POSSIBLE urinary tract infection. The drug was Keflex and I took it last night. My doc's office called this a.m. to check on me and the nurse said that's not what we would give. I should have asked her if there is something else they could call in for me, but didn't think of it. I looked it up online and most of the websites said it's a category B drug. So I don't want to get a rx filled and take it if 1) I don't need it - no burning while urinating and 2) if there's any possible risk to the baby.

So, what should I do? Should I call my doc's office to get another rx or get this one filled? Or what would you suggest?

Thanks!