Wonderful news! IBD is a pain to deal with, but you can manage it, and more important, it's not cancer! It may take some trial and error to figure out what she can eat, and what triggers a reaction. Start very, very simple, one or two ingredients, and slowly add things, one at a time, so if there is a reaction you know what the culprit is. You are probably going to have to do home cooked or raw, it sounds like her case is too severe to ever go back to commercial food. You just don't have the ingredient control you need. Turkey and duck are other things you can try, they are different enough from chicken.
It took awhile to figure things out, but once I did, my Fletcher ate well, and was a happy healthy boy for 11 1/2 yrs.