Had unprotected sex after 10 days of the start of my cycle & 4 days after the period ended & took levonorgestrel. on day 16 of the cycle there is bleeding lasted for 4 days & increased on the 2nd day. is it implantation bleed or my period came early.

After hormone dose: Emergency contraception (EC) pills are used after sex to lower the chance of pregnancy by about 70-80%. EC is a higher dose of birth control hormones. Irregular bleeding or spotting is a COMMON side effect. Nausea, abdominal pain or cramping, and fatigue may occur, but symptoms resolve in a day or two as the drug leaves the body soon. A home urine pregnancy test should be done 3 weeks after sex.