I ended my period five days ago and still have pink and brown spotting what could cause this?

Irregular bleeding is  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.