I started spotting pink a week a go, on the Friday it turned heavy bleeding and lots of clots. I'm still bleeding 9 days on. What could it be?

Irregular periods. Irregular periods are one of the most common problems Obgyns treat. If this is a 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. The pain and discharge need to be evaluated by your doctor for infection.