I'm not going to be able to help on this one. I've never seen a case as this is endemic to an area well away from the Midwest.
We do have our share of fungal infections, histo, blasto though. Very often there is secondary bacterial infection, that may be why the Baytril helped. Sometimes the WBC hasn't had a chance to catch up with the infection, I've seen roaring pneumonia with little lab work to support it.
Just keep talking to your vet, I would have recommended another X-Ray in a couple of weeks (or earlier if no improvement) to rule out cancer.
