Ruptured air sac vs. Sour crop?

[Fidderfarm20]

I have an 8 week or so old chick that has a large lump in her breast area. She is eating and drinking well, feces are normal, and activity is normal. I’ve checked for all signs of sour crop and just can not make the determination of what I’m dealing with here. No sour smelling breath, no white lesions in the mouth, crop has some food but doesn’t feel overly full or impacted. They are definitely rowdy at times so she could have injured herself and caused damage to an air sac. I grew up on a farm and have spent my life working with animals however caring for chickens is new to me. Please help!

 

[cherrynberry]

That does very much look like sour crop a normal crop should look like this even after the chick eats...

 

[Eggcessive]

Cannyou check her crop first thing in the morning after she has slept, but before she has a chance to eat, to see if it has gone down. How does it feel—firm or soft and puffy?

 

[Fidderfarm20]

I’ve withheld food for a short period today and even after that it’s soft but like a balloon. You can feel grit or grain in there but it too is soft and freely movable. When I massage her crop the air will also at times pop side to side. I will check her first thing in the morning.

 

[Fidderfarm20]

The area is still completely the same this morning. Balloon like lump seems to be filled with air is still the same size. She is still BAR. Should I follow this sites directions for sour crop and give her ACV with water?