For about a month now I can hear little sneezes from my pullets. It is not very often and I can't tell which ones are the sneezers. I put them on Duramycin-10 for 10 days and have seen no results, the chickens are still sneezing. One of the pullets seems to want to keep one of her eyes shut also. She will open it when needed but obviously does not want to. I can see no discharge or oozing of the eye. None of the chicken have any nasal discharge so weazing. What should I do now?????