What Are The Side Effects Of Emergency Contraceptive Pills?

Hello my is shakara and I been having alot of problems like I was on birth control but I missed then a couple of time and having unprotected sex with my husband like a couple of days to a week later I started spotting for a like to weeks and I missed my period, having lower abdomen pain alot, lower back pain, nausea, vomitting and tireness but to pregnancy test came back negative