Some women will use oral contraceptives and simply skip taking the placebo pills during that month, going right to another pack of active (hormone containing) pills. Sometimes this works, sometimes it doesn't.
Call your Gynecologists office back and ask to be worked in. All offices have appointments that end up being cancelled.
An ER visit will likely mean you might be sitting in the ER for a while and then be checked out by a physician who is not familiar with your medical history. Better to try and see the physician who is familiar with you.
Have you thought of calling your Gynecologist to make an appointment to get this abnormal vaginal bleeding looked into medically?
Hopefully this is not a serious medically issue. Perhaps it is due to a uterine fibroid; a benign growth in the uterus that can cause bleeding if it expands into a blood vessel. Menopause has nothing to do with this since menopause is the cessation of menstruation.