This is what happened to me. I don't want to give you incorrect information, because I am a beginner too. I found my chick (8 weeks old) lethargic, wings droopy, wouldn't eat, would kind of peck, but miss the food, so I felt of her mushy crop at 6pm when all my other chicks were hard and full/bulging in comparison (after feeling all over her and searching the internet) and decided she had sour crop. I keep on hand NATURAL apple ceider vinegar and had a new bottle just because of some 'tidbit' I read about putting in the chicken's water for...?? I don't even remember why I have it, but I did. I put a tablespoon and a half in a cup of lukewarm water and drew it up into a syringe and fed it to the poor baby. she seemed to like it! So I waited about 15 minutes..then I gently massaged her crop and then inverted her a little and made her burp (gently massaging her crop) The burp smelled bad...ok, I'm on the right track...so I gave her another dose of ACV and left her alone for a half hour...her crop was gassy and mushy again so I did the same..massage, invert and she regurgitated a little.. turn her back upright and leave her alone because I don't want to make her suck the mucus into her lungs and get pneumonia... Leave her for an hour and before bed,vinegar her again, burp her again (massage with her half upright) and put her to bed. The next day, she was about 50% better.. trying to eat and much more alert, but still not great. So I repeated the process. When I got home she was a lot better! about 80%, so I gave her a little ACV and put her to bed. Next day, she was normal...a little puny, but acting like a regular chicken. She acts like I pulled a thorn out of her paw! Very tame.It was soft and watery I guess? It definitely was not full... it just kind of felt like when they wake up in the morning, just empty. Not really squishy like a water balloon. What did you do to fix the sour crop? She is nibbling at her food now and at scratch grains. I also added a tiny bit of hummingbird feed to her water to give her some sugars, not even a teaspoon, she seemed to like it a lot before bedding down again.
Again, this is just what happened to me. If you suspect Sour Crop, go to Wal Mart and get some apple ceider vinegar the NATURAL stuff that is cloudy and nasty looking and dilute it and wake her up to feed her a little bit. I wouldn't delay, but I'm a little more tense about this stuff than most people. If you are wrong about the diagnosis, the ACV won't hurt her!