Hi,
It looks similar to a problem I have seen on here with a couple of hatchlings?
The duct draining the "tears" from the eye was blocked which caused a huge fluid build up. Here are some of the links.
Clutch 16 on this page.
http://ball-pythons.net/forums/showt...%2A%2A+swollen
In the hatchlings it was probably something develomental but, since your snake was fine before hand it could be something as simple as substrate/ snot/ infection blocking it.
I would try and have a look at the roof of her mouth to see if there is anything obvious but booking a vet visit would be a good idea in case it is an infection or something.
Hopefuly it is fixable.
dr del