Is your Teil a Male or Female, because if it's a Female she maybe egg-bound, I would seperate the sick teil (unless this causes more strees on the bird) and give it more warmth, in special heat lamps/warming pads if you have them,are they inside or out? if outside definatly bring it in, offer any favorite food such as millet spray, and take to a vet a soon as possible. Some people use a glass aquarium as a hospital cage to help keep the bird warm, and hotwater bottles ( not boiling) with towels ontop. Let us know how you get on, I hope everything turns out OK.