My sister has an iud and she's very much sexually actively, she bled heavy for two weeks straight a dark black brown blood color. She feels inside her is swollen l( like her ovaries) and she has constant cramps. Also she has the dark line from her belly button down but she says she's always had that. She's very concerned and I'm just trying to help. What could this be? She's worried she might be pregnant again. She's always making an appointment with her gyno soon.