With such long-term changes in the menstrual cycle, we recommend visiting a gynecologist to identify the causes of cysts and prescribe treatment.
You did not write what kind of cyst. But I think most likely you have a corpus luteum cyst, since the doctor said that everything will go away, often such cysts develop within 2-3 months, after which they spontaneously disappear.
Factors contributing to the formation of corpus luteum cysts: Inflammation in the appendages. Malnutrition or starvation, Physical activity and prolonged stress. artificial termination of pregnancy. Hormonal contraception. Preparation for in vitro fertilization (IVF).