at wits end with this small pullet dont know what to do to help her

[Opiumbrella]

i thought she had sour crop, treated for ten days with medastatin, and slso found she had ruptured an air sac. deflated it and she seemed to be getting better for a day or two, her crop was down, and she has been eating and pooping regularly this whole time. it seems now that her air sac ruptured again, but i cant get it to deflate like last time so im not sure. today she didnt want her feed, so i gave her a few small BSFL for some nutrition, and i ordered doxycycline in case she has an infection, as that is the only thing i can think of at this point.
if anyone has any ideas of what may be going on, or that i can do to help this baby, ive spent weeks hand nursing her, barely sleeping, and i want to try and save her if i can.

 

[Wyorp Rock]

Photos of chick and poop?

 

[Opiumbrella]

Photos of chick and poop?

i have no way to post photos as i lost my phone last night, however her poop looks like normal healthy poo, not ruuny, or off color the normal dark clumps with the white capping, as all my healthy chicks and chickens have. she has been eating and pooping, so i know she is getting SOMEthing through her system, but she is skinny and not growing.
i was examining her and trying to see if it was air and food/liquid in the crop, or just food/liquid in the crop, and i tilted her in a way that she started emptying her crop. so i went with it. i got 2/3 of the goop out, and wanted to give her a rest. it was just brown goo, but didnt have a super foul/pungent odor.