It may be due to Stress, iron deficiency Anemia, Vitamin deficiency, other mineral deficiency and PCOS. Most probably you are suffering from poly cystic ovarian disease. In this problem instead of follicle rupture and ovulation follicle is transformed into small cystic structure along the periphery of ovaries. Regular female hormones are insufficient to maintain regular periods may also causes acne pimples And hair-loss with some weight gain in some cases.