Sorry I missed this one.... Many things can cause this, and in mine it has been has a bacterial infection, coccidiosis, worms or all three. No way to no which one it was because I treated for all three and they got better. I don't know much about botulism, but if I remember correctly, they usually die in 24-48 hours? And isn't a limp neck usually a symptom?
A picture of the poop would be very helpful.
Its going on a week. Im just gonna process her and sell the last duck i have. The place im living in now is to much of a crap hole. That Im done with birds. Not getting no eggs thanks to a ton of rats im only apparently feeding. Because there breeding in a garage with junk in it. This place is a rat breeding junk hole ive lost more birds here then where i use to live.