Is the poop rather dark or bright green? It might actually be the botulism if he had that - coming out. If it's dark green and he's not eating much, it could be the bile from his system. Are they for sure runny right when he drops them? versus when you find them? Sounds great so far. Peddling. He's trying hard. How big a bird is he? The sling helped as it was less stressful for my Dingey chicken to start to exercise resistance with her legs - because she couldn't fall down, but she could eventually push with them. Mostly she pushed to turn herself around if she was ticked at me. lol And eventually she pushed herself out of the sling and across the cage. Great day, that. If not a dust mask (which I chose for breathability of the material) you could make something similar out of something soft like fleecey material that helps against bed sores, for example, if you wanted to try it. I still recommend elastic bands to hold it up as that allows for some cushioning if they start pushing themselves.