HELP! My chin has breathing problems

So I have a 5 year old chinchilla called Boo. Her cage mate Chinney sadly passed away Last October from upper respiratory tract infection. She was 12. Later on boo started to breathe strangely too and became a bit breathless so I took her to the vet and they gave her antibiotics and mucolytic medication. Her symptoms subsided so I thought everything was fine until recently.
Boo is now breathing heavily and her breathing problem worsens when she exercises And takes dust baths. We put her in...

HELP! My chin has breathing problems