During the fertile or ovulatory period, preejaculate can be causing conception as it contains enough sperm. It is not necessary for proper intercourse to happen at this stage. Emergency contraception
can give you proper protection the sooner you take it after the act, usually within 72 hours. Beyond this period, protection cannot be assured. Your symptoms are likely to be due to the high hormone content in the pill. Please get a proper clinical examination if you become overdue by ten days for your next period. Hope this helps.