It can also be atrophic vaginitis which is common
in post menopausal women and
in your case heralds a hormonal imbalance. It could also be chlamydial infection or even gonorrhea. Hence it is important to get a complete STD and a complete hormonal panel (estrogen, progesterone, FSH, LH, prolactin, thyroid) done. It could also be due to infection in the uterus, cervicitis, vaginal infection.