I had my period a week an half early and it las 4 day. but i been sporting dark discharge since then, what are the causes for this?

Common problem : Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections & hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.

GYN: Causes can be anything from pregnancy to infection. Depending on your medical history and other symptoms an evaluation by your gyn may answer your question.

It depends,,,: This depends on some factors. First, it just might be the last of your period, with old blood and tissue. It also could be due to an iud (intrauterine device), if you use one, as these are notorious for long term pelvic/uterine infections as complications and so, it can easily be pelvic inflammatory disease from a bacterial infection. It might be a std like chlamydia, etc. But is less likely.