A 49-year-old female patient complains of itching, burning in the external genitals, frequent urination. The symptoms have been present for the last 7 months. The patient has irregular menstruation, once every 3-4 months. Over the last two years she has had hot flashes, sweating, sleep disturbance. Examination revealed no pathological changes of the internal reproductive organs. Complete blood count and urinalysis showed no pathological changes. Vaginal smear contained 20-25 leukocytes per HPF, mixed flora. What is the most likely diagnosis?