Chinchilla with swollen finger

Hi all, my chinchilla has a swollen finger on his right paw and he is favouring this paw by holding it up when he rests. I'm not sure how or when he got injured but I'm guessing he could have gotten it caught/sprained as I couldnt see any open wounds or cuts on this finger. He's still using the paw to hold his chew toys or to wipe his nose although he does not seem to have as good a grip as usual. I also catch him licking/grooming this finger sometimes. I've heard that chins sometimes self...

Chinchilla with swollen finger