Media playback is unsupported on your device Video 'I fled Boko Haram and had to leave my son behind'
Nigerian authorities say 22,000 people have been registered as missing in conflict.
The Red Cross however said the true number could be higher.
Asibi's son is among those missing.
She tells the BBC that she can still remember the moment she left him behind while fleeing Boko Haram five years ago.
Her son's feet were numb because they had been hiding in a river all night and he couldn't travel any further.
Video producers: Naomi Scherbel-Ball, Mayeni Jones and Ayo Bello. 14 Sep 2019