balding mother finch

Question
Hi - we have had a pair of finches for about 2/3 years who have since had 1 male and 3 female babies now about 18mths old - the mummy finch has lost her tail feathers and some wing feathers and now sits in the bottom of the cage facing the corner trembling.  I have seen her on one of the perches but she generally seems unable to do anything but hop around.  When the other birds come to the floor she hops out to see them.  Any advice please on what is wrong?  Many thanks.

Answer
I have only one piece of advice you need to follow:
GET THAT BIRD TO A VET! You have a severly ill bird on your hands! The sooner you get that finch to a vet the better chance it has for survival.
While waiting for the appointment (if you are unable to get an emergency appointment), turn up the temperature of the cage (I am assuming you have a heat lamp on the cage at all times) and do your best to keep her comfy until you can get her to the vet.