Have a duck who has been limping , not walking on one leg well. Have been giving the duck(s) brewers yeast along with food. The duck has been able to balance (after a couple of minutes), walk around, get in/out of kiddie pool (supervised), and can go up/down a small ramp into the duck house. Today the cat got close to the ducks , but did not touch them in anyway. Most of them got up and walked away. One chased the cat along the fence line. The duck who has been limping tried to stand , but couldn't. Instead the duck fell to its side kicking legs. The duck is unable to stand at all, lays on side, will sometimes scoot on stomach using legs to try and move itself. It has been several hours. Drank once that I have seen. When trying to stand (with help) moves head left/right and flails legs, but can't stand or seem to balance itself at all. Is it possible the duck is still in shock or maybe suffered some type of stroke? The duck is about 4-5 weeks old. First time I've had ducks. So should I allow more time or is there something more serious going on that the duck should be culled? I would hate to cull the duck, but don't want the duck to suffer in any way.