Fighting has displaced at least 262,000 people since March, according to the UN's humanitarian agency OCHA, with many of them gathering in squalid camps near Goma.
In one camp for the displaced in Kanyaruchinya, "Furaha" [ all names changed to protect identity] described in tears how rebels kidnapped her 15-year-old daughter in May, before releasing her two days later.
"She refused the advances of the militiamen," the 45-year-old mother said, inside a makeshift hut of wooden sticks and tarpaulin.
Fighters came to her home in the dead of night and snatched her daughter, then raped her, she said.
Just a few days later, Furaha too was sexually assaulted, she said.
Men in military uniform attacked her and a friend while they were harvesting potatoes in the village of Nyesisi, north of Goma.
"Three men raped me, and six raped my friend," she said.
AFP was unable to independently confirm the account, and the identity of the attackers is not clear.
Some 70,000 people live in the Kanyaruchinya camp, in ramshackle tents and makeshift dwellings built on top of mud.
Another woman, "Mwiza," who is also from Nyesisi, told AFP that two men in "Rwandan army uniform" had raped her in June.
"I ran away to go to the hospital," she said, her head bowed while she fiddled with rosary beads.
The doctors advised her not tell her husband about what happened, Mwiza said, "so that he wouldn't chase me away".
Didier Buindo, a doctor in the camp, said he'd treated about ten rape victims in November alone.
Sexual violence is also occurring in the displacement camps, according to the doctor, who pointed to a case in another camp where two girls aged five and 16 had been raped.
"Mutoni," 22, also has a scar on her face from where she was grazed by a bullet in August.
"An M23 fighter shot me at point-blank range," said the woman, who fled her village to seek refuge in the displacement camps.
Mutoni survived the attack.
But her young niece, whom she was cradling in her arms, was killed instantly by the same bullet.