An upsurge in Boko Haram attacks and returnees from Cameroon are stretching camps for those made homeless by the conflict to breaking point, as the UN warned against forcing people back to northeast Nigeria. Obinna Orjingene is a doctor for UNICEF in the town of Banki, near the border with Cameroon, where the population has jumped from 32,000 to 45,000 in the last few months alone.