Sorry to hear about Lucy. Seems like she is on the mend though
As I am a newish Yorkie owner, I can't give advice on food. Having said that, my Bailey, who is 1.5 years old, only gets kibble and the odd piece of chicken, rice, veggies (no celery). He sure loves his bits of apple once in a while
All the very best to you and your Lucy!! You are both in my thoughts.