I've been bleeding for 3 weeks in a row is something wrong? this the second month it happens i didn't have a period for three months before that

Your hormones are in: .. flux for some reason. Irregular periods and spotting could mean you may have some hormonal imbalance that could be affected by many different factors, including age (if approaching menopause?), nutrition, illness, exercise (or lack of it), body girth, psychological well-being, stress, season, or simple fluctuations of other related hormones (thyroid for example). U should see a GYN to help.