Hi, I'm 23 Years Old Girl. I Had Unprotected Sex

Hi, I'm 23 years old girl. I had unprotected sex with my fiance on 24th dec and took ipill on 26th dec. I ended with my periods on 24th dec only (the day i had intercourse). After taking ipill i again started bleeding on 30th dec, it was very heavy that i took trapic mf to stop or reduce the bleeding. it stopped after 4-5 days. Then after two days of stopping i again started feeling uneasy as if my periods will again come! but hadn't come yet.
What could be the reason to this?