I started my period but been light like pink /red color been almost spotting my whole period and lower back pain but feel fine no sick or nothing ?

Light pink 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. Don't worry about the color that is not clinically important