Hi..Emergency hormomal pills contains progesterone which is one of the hormones which maintains the menstrual cycle and period bleeds.. These drugs are known to cause few side effects such as irregular periods, heavy bleeding, headache and other symptoms.. Your symptoms may be related to the same condition.. They are rarely permanent feature and will improve during your subsequent cycles.. And also there can be a small possibile chance of the bleeding being a symptom of pregnancy, if you have had unprotected sex recently.. Know about the other symptoms of pregnancy and get a pregnancy test done, if you have any such symptoms..