What Causes Pain During Sex And Yellow Discharge?

My daughter had signs of herpes back in Dec. 2009. Turns out she was diagnosed with Herpes Simplex I but in the vaginal area. Two weeks prior to this diagnosis, she had a yellow discharge. She was tested for STDs back in December and again last week. The tests came back negative. She waited here in Australia 6 months to see a gynecologists and when she finally had her visit, she was seen by student doctors who could not answer either of her questions which were (1) she has a pain that she gets during intercourse and has had it for 6 months now. The student was able to probe with her finger and hit the spot in her vagina where the pain occurs, but the student offered no advice other than come back in three months and weâ??ll do an inspection with a camera if you still have the pain. (2) As to what the yellow discharge could be from, she was told maybe it could be related to the herpes, but the one and only outbreak she has had has been over for a more than a month, yet the discharge continues for over three months now and preceeded the herpes. Numerous medical sites on the net say that although a yeast infection often produces a white discharge, it sometimes can produce a yellow discharge , although less frequently than the white discharge experienced by most females.
How can one tell if they have a yeast infection (i.e. and one that is persistent at that)?
And, what are the top two treatments for a yeast infection?

Even if it turns out she does not have a yeast infection, since medical treatment has been lacking for my daughter here, we need to at least eliminate that the yellow discharge is from a yeast infection. Again, she has had 2 STD tests already and seen a doctor and gynecologist (student) and none has been able to isolate what is causing her vaginal pain during intercourse or the yellow discharge.
Awaiting advice. Thank you.