Going from a rack to a 55gallon is a big change. I would block off part of the tank for now so she feels more secure. On your next feed try a live rat pup and if she doesn't take it right away leave it over night, the pup should be young enough that it will not bite the snake.

Thats how I got a female that hasn't eaten in 6 months to eat. Hopefully it will work for you.

Don't let it get to you, it happens! They can go a very long time without eating.

Richard