I am not sure if I'm pregnant, is it safe to take any medication?

When did you engage in the unprotected sex your concerned about? You can take plan B up to 72 hours after, but most effective if taken with in 12 to 24 hours.

Also if I read your post correctly it is only 6 days after your period? So depending on the length of your cycle, it maybe too soon to cause pregnancy as sperm can only for about 6 days.