He's a long way from where I am, but you're right, I do have an endoscope!From just the one nostril narrows it down a bit to something local like foreign body, tumour, injury. How old is she Nesi? Any rat baits around? An xray or scoping it may be usefull but without that you are just guessing but even looking down the nostril with a bright pen light might see something or even one of those fibre optic video cameras for looking inside an engine might help, I'm sure an inquisitive mechanical man like you has one Nesi.
Ken
yeah, maybe she did it fighting!Maybe she bumped her head on something and burst a blood vessel in that nostril and the pressure of the rag stopped it.