We have 3 three week old khaki campbell ducklings who have seemed fine and healthy until today. The drake seems weak--kinda wobbles a bit and doesn't seem to have much pep. He is drinking and eating a little, though not as much as the others. He seems to hang back and let the others eat, then kind of picks at the left overs. We are feeding them non-medicated chick start and grow, along with lettuce and occasionally yogurt. We have him in a separate box with water and food, but this is our first step into the world of birds and we have no idea what to do. If anyone has any idea what we should do, please let us know.