I'm 18 and been spotting for over a week instead of having my period. it's dark brown. i'm not on birth control and never had sexual intercourse. ?

Spotting: The spotting might actually be a period. The main reason for light periods is change in hormone levels. Causes for what seems to be a light period can include: thyroid problems, eating disorders, excessive exercise, initial periods for a girl, use of an intrauterine device, oral contraceptives, perimenopause & implantation bleeding in early pregnancy which rarely occurs.