This month, my period is mostly brown blood. It started on time, but it's different. No unprotected sex so unlikely it's pregnancy. Concerned...

Take a test. 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.