It could be the dust in the straw or more probably fungal spores in the straw Andya9. We have had severe respiratory infections develop caused by fungal spores. The symptoms were as you describe. Initially a husky voice with no nasal or eye discharge. Then developing into an inability to crow and raspy, wheezy breathing. My advice is to ensure you have adequate ventilation in the coop at night and change the bedding to something you can be sure is properly dried, like Aubiose (hemp stems) or quality wood shavings.