hi ! period irregularities are now one of the very common conditions women are facing, and due to hormonal disturbances the suffer from FIBROIDS, PCOD,THYROID etc, and they delayed or early periods, heavy or scanty discharge, pain very mcuh, loss of hair, growing wt etc, but in this case she is also having frequent fevers, if this fever is associating with her periods then it might not be nrml fibroid or cyst, it might be CHOCOLATE CYST, which is somewhat a serious one troubling very much than nrml cyst. if the fevers are not associated with periods, then she might be having, accute tonsilitis, throat or lung infections. have an ultrasound of abdominal and chest x ray done and consult a good gyaecologist and go for medication. you will be cured completely.