One thing I found was that food which can be licked or lapped rather than chewed in any way, was often much more tolerable to Darcy when she was feeling unwell. I've spoken to other people who have said the same thing too.
One random thought regarding mouth ulcers. I don't know if Darcy got actual ulcers (we never saw any) but something certainly happened because prior to amp/chemo, she would eat crunchy foods but during and afterwards, she would not. As an example, she used to love treats made out of dried fish skins (ewww) but they're really hard and crunchy and now she won't eat them at all (unless I bash them into tiny bits).