Hello, Thanks for trusting us with your health concern. As the emergency contraceptive pill contains high dose of progestogen, these side effects are common. The bleeding you are experiencing is due to the withdrawal effect of the hormone. Your next natural period also may get delayed by a week or two. Please see a specialist for further evaluation if you become overdue by ten days. You can have supportive treatment for the symptoms like using an analgesic for the headaches, an anti-emetic for the nausea etc. and increase the fluid intake. The symptoms subside as the hormone status returns to normal. Hope you find this information useful. Take care.