Hello, Irregular periods is caused by hormonal imbalance (like prolactin, oestrogen, progesterone,) hypothyroidism, reproductive tract infections, PCOS, anemia,fibroids, stress etc, you need to be examined first to find the cause, don't worry all can be managed with medicines please consult a gynecologist. If you already consulted a doctor and they adviced regular medicine, then you need to take them instead of changing doctors. Some disease (like PCOS) needs treatment for months. Hypothyroidism for life long.