BV TMI and question..

I got treated for it with the gel and oral antibiotics. I got tested again like a month later and I still have it. Does that happen a lot? And since I still have it, shouldn't they have prescribed me a different antibiotic? I think I got the same one. How do I prevent them? I'm not a dirty person or anything so please don't think that! Also, does my SO have to get treated? Or just me?
Thanks in advance and sorry if this grossed anyone out.