It is kind of a strange situation. This guy takes his yearling peacock to the vet. While he is at the vet he post a pic on Zazs Face Book group. A couple of people say that it looks like Blackhead because the head is contracted and the wings droopy. The Fecal float shows nothing, the 'avian' vet doesn't know what is wrong and they send him home with a $200 bill to pay and no help for the bird at all.
Now all the good intentions from the internet experts are telling him to treat for blackhead and blackhead only or his bird is going to die.
So the guy went to Walmart and got some Fish Zole and baby food and was on his way home to either drench or tube the bird. Now he posted back that the bird died and in the necropsy he found 10" of baler twine in its gut. Yeah, I mentioned that my last hen to die had died from having a twisted up gut from eating moldy feed. Not everything is blackhead, cocci or worms when a bird is sick, but it is a good place to start.