Suggest Treatment For Irregular Menstrual Cycles

Hey, i haven't seen my period in 5 months, however last month i spotted for a few days and it was almost dark brown/black, i feel tired all the time so it is hard to concentrate. My urine also had a strong unpleasant odour, so i assumed it was because i wasn't drinking enough water, but i don't think that's the reason. NB- i've been suffering from irregular menstrual cycles since i was 15, I'm 20 now, and there is no possibility of me being pregnant