I just had one with sour crop two months ago. Basically her crop had been plugged up by eating some really huge strands of grass that she got her little beak on! They came out the other end totally undigested in big clumps. I have an avian vet that we're friends with so she treated my chicken. She ended up having an infection in there so she was on an antibiotic for a week & reglan (rx from the vet that encourages the crop to empty) for a week. I noticed that once things started "moving along" again, she started acting better. It took a few days for the crop to really go down & empty as it should. I isolated mine so I could really keep an eye on what she was eating & what was coming out. Once her poop started looking better, she was improving. Hope she feels better soon!