Hi there i understand your concern...it may occur in women who have anemia i.e low haemoglobin levels,diabetes or thyroid problems. It is also common in women with high levels of a protein called prolactin in their blood...it can be the side effects of certain drugs like oral contraceptives,antipsychotics,antiepileptics...it may be due to poly cystic ovarian disease as well... So I would suggest you to consult nearest gynecologists for detailed clinical examination and evaluation they will do the needful.

If you really want to know the root cause of this issue and heal, please read my blogs on www.truhealing.com or practo health feeds. Hope that helps

You should get an ultrasound pelvis and hormonal profile of you done.