question: I was just prescribed doxycycline and metronidazole for a bacterial infection that I received sexually.  I would like to know what caused this?  Does this mean that the guy that I was with has been with someone else or did he need to wash or take a bath before he was with me?  I want to know if I need to stay away from this guy because he may be having sex  with someone else that has a bacterial?   No one has explained the causes to me and I would like to know to avoid this from happening again please.