Hi StephanieR,
wheezing could happen from something getting stuck in the throat, but I think you've already picked that it may be a respiratory disease (hence the Duramycin).
I wouldn't have started antibiotics myself just yet, as it may mask other symptoms without completely removing underlying germ causes (if there is one there, e.g. mycoplasma gallisepticum) and it certainly won't help if the disease agent is a virus (or if it's a grass seed stuck). On the other hand you obviously don't want to lose her, so that's your choice.
If it was my bird, I'd probably remove her to a warm spot where I can observe her and so she doesn't transmit anything, and check for runny nose, sneezing, rattles, gurgles or other respiratory signs (e.g. wet area under the wings of a morning, after sleeping with her head tucked there). I'd also watch for signs of coccidiosis (going off feed is the first symptom; then you see listlessness, droopy wings, hunched appearance; often there's blood in the droppings but not always). She may need treatment with Sulmet or Corid, but I emphasise 'may'.
These are just my initial thoughts, not an expert by any mean,
cheers
Erica
