What Is The Treatment For Vaginal Infection And Irregular Menstruation?

hello doctor, i wanted to ask you about the infection of vagina. My girlfriend & I had sex on 27-03-2011, she was to have her menustral period on 25-03-2011 but she is having irregular periods, for which she has taken DUB 5 for ten days after that she had periods on 12th april. she was having white vaginal discharge before the periods also after taking dub 5. she consulted a gyne who advised her that she use vaginal pessaries & a local application to be applied on the vagina outer. after this she was treated of the discharge & now since last 3-4 days she is again having that discharge.

I want to ask whether these problems of discharge is due to the sex that we had for the first time as she is a virgin or do i need to take some test to detect if i am having the infection that is trasmitted to her.She is 25 yrs of age & is of average weight. pl advice