Plan b side effect

Patient: Hi, my gf took plan b in december 2 and in december 8 she started to bleed only slightly, a month pass and on january 3 and it lasted for 7 days and it was a lot, her lower abdominal was hurting a lot and after the 7 days she still has the abdominal pain and lower back pain. is this normal is it a side effect of the pill or do you think she is pregnant?