Our mouse

Question
Hello,
First of all, we dont keep mice as pets (sorry), but we keep them on hand for our snake.  We usually buy 5 breeders at a time and keep them in a 10 gallon aquarium until its feeding time.  I was doing laundry a week or so ago and found one of the mice from the previous batch I had bought running around. She looked pretty chubby.  Now, she looks HUGE - I would guess pregnant.  The problem is, she is very lethargic, barely moving, looks like she is on deaths door.  I dont know if she is about to labor or die, since I am not familiar with mouse behavior, other than they run like crazy on their squeaky wheel.  She is not mobile at all, just laying there in her bedding, eyes slightly closed.
If she is in pain from dying I dont want her to suffer, but it would appear she is suffering anyway?
Thanks for any reply you can give me.

Answer
She has probably been over bred. Pregnancy takes a lot out of a mouse and leaving her in with males means she is continuously getting pregnant.

The feeding of live animals is seen as unfair, inhumane and cruel and is already banned in countries such as Europe, USA and South Africa. Feed your snake frozen food or 'snake sausage.' Not only is this far more humane than throwing a live creature in the tank, but it's much safer for your snake, those live creatures can fight back.

Please don't keep mice without doing some research. Please note her death will cause her no more suffering than being fed to a snake. I recommend taking her to the vet.