Had sex one week before period. 5 days delayed then got brown discharge and 1 day period. what does that mean?

Common: 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.

Pregnant?: If you are not using any type of birth control, its possible you are pregnant. Discharge and a 1 day period doesn't sound like a normal period and could be pregnancy related bleeding. You should get a pregnancy test. You can get one to do at home at a pharmacy without a prescription or see your Ob. There are other possibilities such as an anovulatory month. Best wishes!