I started spotting every 2nd day since cd18. period due now but just clots being shed. no blood flow as normal. i've pms symptoms and no usual strong?

Common problem: 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, polyps, fibroids and hormonal changes can cause spotting. If concerned for pregnancy then do a home test . There are many options available to help regulate the menstrual cycle. Schedule a visit.