I am having this brown discharge for one week now and it happened 2 weeks after my period.. my period is regular. lower back cramps, headaches, moody?

Brown = blood: 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.

Vaginal discharge: A vaginal discharge could be caused by various reasons but when pain is associated, especially pelvic pain it needs prompt evaluation. If you develop fever you should go to the ed. If pain is not severe you at least should make an appointment as soon as you can with your gyn provider.