Snake abscesses don't drain on their own, they need surgical (vet) help, & probably antibiotics too, but antibiotics alone won't do it. Poor snake, I hope you
can help her recover fully. Can't say, it could have been just from the filthy cage, or rat injury, who knows? Her eyes do seem a little big to me, or maybe it's
the contrast- the lighter color makes her pupils really stand out. Pretty eyes!