I have some runners and a few Pekins who have been exhibiting strange symptoms. I've never had my ducks act this way before. They are loosing control of their legs and throwing their heads back. I thought it could be botulism, as they had gotten in the pig pen and ate some old watermelon. We have been treating them, just not successfully. We have lost 4 of the littler ones. Their age range is between 6 weeks and 10 weeks of age. We have two more who are sick like this, and the rest seem to be fine. Any ideas on what it could be? I don't want to lose the other two! Their coop and run is CLEAN. I can't figure it out!