The Corid will not hurt even if Coccidiosis is not the problem.
BO's can look a bit odd when small, I agree, but with your concerns and her behavior, I'd treat all of them.
How is she doing?
Photos of her and her poop?
Being puffed up, heavy breathing and holding her wings out, I'd begin treating for Coccidiosis.
Liquid Corid dose is 2tsp or Powdered Corid Dose is 1 1/2tsp per gallon of water given for 5-7 days as the only source of drinking water.
Do not add...