5 days after i took plan b i started bleeding, it lasted for 3-4 days. 10 days later i started bleeding again which lasted for 4 days. is that normal?

It can be: 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. Also, be sure to put in place a good Plan A, so that Plan B will not be needed again.