Suggest Treatment For Delayed Periods

im 22 years old my height is 5.1 and weight 5kg,i have lose about 5kg weigh in the months of april,may,june and i was continuing my with my diet plan but from the month of july im not having periods(its been 2.5 months i have not got periods) i have improved my diet from july by taking dates,fruits,milk but no use in the mid of august i just got few spots of blood but that also stopped within 1 day plz tell me what i do should i take pills?