ive read some sites that say this is present in a womans vagina aready,then it says a man carries this bacteria and passes it to a woman but it says also it not sexually transmitted,so how can a man be a carrier?then it says men produce an antibiotic to cure himself,and also he can be treated as well as the woman,im very confused!is this an sti?ive never had this until 3months ago,i only get this when ihave unprotected sex,we been checked for all std and we are negative ,its never happend before until 3months ago ive been with the same person for a year,whats wrong?please help me to understand this better .thanks so much.