Very light period this month(early also and short), and now i have had cramps for the whole month.back pain took a test and it was neg.could i be pregnant

Light 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. Need to ensure that you take the pregnancy after you miss period.