Wish I could be on more regularly. Finally drilled back to these pictures, & been following some. Looking at the pictures, other than the swelling and your reports of how her breathing sounds, it is somewhat confounding, isn’t it?
Because she doesn’t look typical at this point for a respiratory infection - though it may very well be. Were her nares or eyes ever wet with discharge? The second thing about this is that Coryza is infectious, or maybe there’s a variety that isn’t? If it is “Infectious Coryza”, then why has it not quickly spread to others in the gang there? These must be questions you ponder too. I am not criticizing, just putting in my two cents to try to help.
I recall watching some video on removing pus from a certain eye / sinus infection that even when resolved leaves the lump of pus blocking normal drainage. I will look for it again as I don’t remember what infection was the cause.