Old hen has right eye swollen shut

[Eggcessive]

I would get the Tylan and start it even though you found the grass in her nostril. It won’t hurt her, and the antibiotic may help, especially if it is a sinus infection from a respiratory disease. Terramycin eye ointment from the feed store also is good to use in the cleaned out eye. Here is a thread about removing eye pus:
https://www.backyardchickens.com/threads/nasty-eye-infection-pics.1071718/