I understand what you are going through (with Sam and Yoshi)
I went through the same thing with Nena..there were days that she didn't want to eat at all..and finally when she ate something, she threw everything up
She was so small and skinny..
But lately she's been eating normal, and the last time I went to the vet she actually told me that I have to watch her weight..I was so relieved and happy when I heard that..because all the other times the vet told me that she was skinny and had to eat more..
I'm really thankful that Rufus has a good appetite
And I really wanna believe that he helped Nena with her eating problems..