What Causes Dark Bleeding After Taking Contraceptive Pills?

Hi, yes my friend got her period two weeks ago which she thought at first was her period then she was bleeding grey spots and it lasted about a week. Before she had her period her breast were sore 3 weeks before. During her so called period she had to wear a tampon and pad and change it quite often. Then about a week later she had sex with a condom but it broke, so the next day she took plan B (the morning after pill) a couple days later she start to bleed brown spots and now is still bleeding? What do you think is happening?