My last period was sept21. i spotted brown blood for 4 days starting the 11 then missed my period this month. i am not sexually active. what's wrong?

Usually regular?: A doctor can check to see if there is a medical issue, if a woman has mild menstrual-related symptoms. Many women have some variation of their mucus discharge, their periods, or a missed period on occasion. Some women feel normal after a few days, but others have bothersome symptoms and follow-up with their doctors. If needed, a pregnancy test is accurate if done correctly after a missed period.

Peri menopause: Sounds like early menopause or thyroid disease.Get a pelvic exam and some bood work.