Hi there! How has been your diet of late? Simple Vitamin deficiencies can cause ill health which in turn can lead to disturbed menstrual cycles. Another thing that could explain your symptoms plus lack of menstrual cycles is Hyperthyroidism but you will usually have associated symptoms like rapid heartbeats causing palpitations. I would suggest you consult a physician and undergo a full physical evaluation as it can pick up signs of Vitamin deficiencies and thyroid disorders. Also get a Hemogram done which can pick up Anemia along with thyroid profile if you have any of the symptoms i described above. Until then a good diet, healthy one with plenty of veggies n water along with 20 to 30 mins of exercise about 5 days a week.