The ducks are a batch that I purchased from an auction. This didn't start until I brought some goats into the mix. These goats were around chickens that were experiencing the same issue. I have had three over the last week just get sick and pass away. One at a time. This time I got to see one before I found it ... well you know, before it stopped breathing. Symptoms include lethargy - it won't move, it was swimming in circles when I found it about to drown. So I saved it, picked it up and it's head just flopped around. It will not eat or drink. It doesn't appear to have mites or any bites anywhere from anything. What sicknesses or diseases does this sound like? Thank you for your help.