Had unprotectedsex in nov, normal periods dec, jan&feb slightly late in march now 3weeks late in april. tummy is tight and cramps. what does this mean?

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.