I got two periods in a month one regular and the other just a lot of brown discharge that fills up my pad i also took a plan b even tho we used protection and my periods are always regular this is my first time something like this has happened ?

About Plan B...: Plan B can alter the menstrual bleeding for the cycle in which Plan B was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because Plan B works most of the time, but not all the time. If the pregnancy test is negative 3 weeks after Plan B, that means a woman is not pregnant from that episode.