My girl and I had unprotected sex April 12 and 21 but did not finish in side her on April 28 we had sex and finish inside and her while on her period than on may 4 and sex had sex and finish inside but she took plan b on the 7 and on may 11 we had sex and I finish inside again she started her fertile week the 12th of may buy on may 13th she started to have some spotting and her Period is not due for another 18 days and today may 14th she's still bleeding what could be the reason???