@happylotus and I had a private message together and I am going to post my comments here so that others can learn and in turn help their birds in the future:
This is awful young for a bird to have any type of crop issue, let alone a sour crop at that. Generally crop issues pop up with free rangers, hens with laying issues or other internal issues where swelling is involved. And of course we can never be sure exactly WHY your youngster has these issues, we can only guess and try different things.
However after reading your letter, two things come to mind that might be causing this...I have seen marble type crops in my broodies....they eat well enough, but don't drink enough water as they are rushed to get back to their incubation duties. Dehydration...Is she getting her fair share of water? If for some reason she is being bullied away from the water in the brooder, she will get these symptoms in her crop. If you think this is the case, I would add another waterer.
The next thing is Coccidiosis...chicks this age are highly susceptible and enteritis goes hand in hand with Cocci. Enteritis is bacterial actually but causes the yeasts in the entire GI tract to go haywire and will cause doughy crops. Do you see lots of whitish diarrhea around, any poop with mucus in it, any amount of blood at all in the poop? Others not eating or drinking well? All these are cocci classics and in the end they stop drinking enough.
Do not use any ACV in the water as it can make the yeasts go more crazy on sick birds. (ACV is a great tonic for a healthy bird)
So what I would do in this case is work on her drinking more water and if I saw ANY of these symptoms in her or others of Coccidiosis, I would start them all immediately on Corid. It's a thiamine blocker and is pretty harmless if used properly. You can get Corid at nearly all feed stores.
These are my thoughts on this. I have noticed that if the baking soda mixture doesn't work after a day or so, this is beyond a simple case of doughy and sour crop...something is driving the yeast infection and that where you need to attack. But of course again, we can only guess. If the chick has a genetic internal issue and something is growing improperly pushing against her crop or intestines, we can't fix that.
If you are seeing even the tiniest bit of blood in the poop, no doubt the crop issue IS related to Coccidiosis. I have seen this many times. Being on medicated feed can HELP to prevent cocci, but it is NOT sure fire. (mediated feed only has a small amount of Amprolium, not enough to treat an outbreak, it is only a tiny preventative) So what you need to do as soon as possible, is get some Corid. You will need to get them off the medicated feed when using this stuff as it will over dose them and get them on unmedicated starter. Coccidiosis kills fast, so I wouldn't wait. If there is a feed store in a nearby town, I would drive there as soon as you can. Corid works very fast and you should see improvement by day 2 or 3. And get them all on this, it won't hurt them. If one has it, they all do.
