My periods have been irregular for the last few months.its a first time i noticed a drop of brown spot, my cycle is on the 17th day.what is the reason?

Doctor can evaluate: A doctor can check to see if there is any worrisome medical issue, if a woman has mild menstrual-related symptoms. Many women have some variation of their periods or a missed period on occasion. Some women feel normal after a few days, but others do have bothersome symptoms and follow-up with their doctors. One cause may be hormonal fluctations, associated with variations in the uterine lining.