I spent $2000+ in four days on a pancreatitis and still lost her. For some dogs, it just is. Nothing you can do to change anything. I spent a year paranoid that I fed something wrong, or that I made too many changes. Looking back, Liesl probably had pancreas/fat absorption issues her whole life. She would get skinny for a couple of weeks, then fatten back up. The last time was just the last her body could handle, and she tumbled into a severe acute pancreatitis.
What I'm trying to tell you is to not be paranoid. Follow the prescribed diet to a "T", but realize that it may not have been anything you did.