I had my last period november 16-20 and had sex on the 24th and the condom broke and i took a plan b on the 26 i bled 5 days later dec1-5 then it stoped. then i spotted on dec 7th . i took a pregnancy test strip and got a fain positive. why?

Can retest in 1 week: Can retest in one week to be sure. A urine pregnancy test gives a reliable result if done correctly. One can test about 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after missing a period. An Ob-Gyn doctor can evaluate any persistent or worrisome symptoms. Using Plan B can alter the menstrual period timing for that cycle and sometimes the next cycle.