I never have an irregular period i was 11 days late and then started bleeding it was light brown nothing like my usual period about 2 days after my missed period i started feeling very nauseated and my breasts are really tender and sore what could be the

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.