What Happens If To Untreated Fungi Nail I Need Chinchilla Help, Are They Sick And What's Going To Happen? How To Treat?

I need chinchilla help, are they sick and what's going to happen? How to treat? - what happens if to untreated fungi nail

I have two chinchillas, a mother and adult son. The mother turned in this year 5, the son of 4 years. The child has no medical history, but the mother had eye problems. They are separated, I'll just run together as soon as I did not notice the problems of the mother. Your skin under herchin is confused and out, but the skin on the buttocks is perfect, and now the son is to INTHE preparationof. My mother said it was a fungus. So how was it? If left untreated, will this happen? Is it fatal?