I missed my period about 4 days ago and today I've been wants seems to be spotting, I'm not having sexual intercourse at all what could be the problem? If there is one?

Irregular periods. 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.