wheezing

We have a Wyandotte cross pullet who's been wheezing off and on for the past few weeks. She seems healthy otherwise. We had the flock on Denagard (the preventative dose) and it seemed that she improved when she was on that. However, they are done with it now, have been for about a week, and now she is wheezing again. she acts fine but i caught her today and put her in hospital pen, and I thought she seemed a little underweight. Not too badly underweight, but a little. I started her on Baytril. Is this appropriate? We have been trying to get the flock over a problem with Capillary worms, and I'm worried that she might have them and it's setting up some sort of bacterial infection. We just dewormed the flock a few days ago, with Levamisole. This is the third deworming they've had since July. (Two doses, a week to ten days apart, each time) Right now, the rest of the flock seems healthy, except we have new hatch chicks today, and it appears two are dying. Hard to say what that's related to though.

Suggestions?