I have had my period for the second time this month and it's going on the third week now there was pain the second week but none the first or now ?

Irregular periods: If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections and 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.