I took emergency contraception and when my menstruation started it has not stopped. it has been 4weeks. i was told by the pharmacist it can affect ones cycle but im concerned this is too long ?

Not predictable: An emergency contraceptive pill can alter the menstrual bleeding for the cycle in which the pill was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because pills like Plan B work most of the time, but not all the time. Cycles should be back to normal after 1-2 cycles. Four weeks seems long, so one can call her doctor for advice.