My IB peacock is sick! Everything seemed fine about 2 hours ago, but now he's on the ground, has his head thrown back, can't walk forward, but struggles backwards! He's been eating and drinking fine until this. I have 6 other peafowl in the same pen, no one else is affected. Everyone was wormed about a month ago with Panacure. No unusual poo. There's been no coughing, or signs of sinusitis. Anyone have an idea?