if the heart or lungs are not the cause, one of the causes of ascites can be cirrhosis / liver disease, you could check if that would explain the droppings as that is tied to digestive system.
To be a bit more uplifting, as all these options sound pretty bad: I have seen numerous posts here of...
Not sure about the yellow part of the liquid, but it looks a bit like diluted yolk or fat maybe but that seems odd, if so the clear fluid could be from ascites (liquid buildup in abdominal cavity). I think draining was the best thing you could do.
Poor oxygenation of the chicken (consistent...