So sorry about your chicken! Can you check her mouth & see if there's anything odd going on in there? If she has no signs of a respiratory infection (other than the wheezing) could it be gape worm?
Haven't looked but don't think it is gape worm. So many times people think that problems are attributed to gape worm but I've never been able to determine if any of my birds have that (by looking down their throat). Guess I could try to flush her nostrils. I've used Vet x (kinda like vicks vaporub) but no improvement with that either. Maybe I'll put her in the bathroom with the vaporizer on. Did that before for antoher chicken but she didn't improve. This gal just sounds very congested and wheezing. Not struggling to breath as bad as one of my birds in the past but still can't stand to listen to the poor thing. Just picked some fresh strawberries from my garden and she scarfed those.