Greyhound not eating properly?

Hello! My 10 year old grey, Addie, after getting sick has not reverted back to her normal eating patterns. Mostly she just won't eat. The vet suggested that we put in some of her favorite reward foods, yogurt and peanut butter, into her food and that has mostly worked. The issue is that she went from "I will go outside just so that they will feed me" to "I must be tricked into eating."

It has gotten to the point where she gets sick from not eating enough breakfast. To some extent, there is only so much we can do to get her to eat but I am hoping to hear any advice. She is getting older, so I am obviously assuming the worst, but she still acts like a weird puppy while ignoring her food. Also, she lost a lot of weight for no determinable reason so that was another reason the vet suggested fattening up her food. I would say she has been having this issue and acting a little weird for the past two months or so. After several vet trips they don't have any ideas but they do not appear concerned.

Any tips, tricks or anecdotes would be much appreciated! Let me know if you need any clarification or what have you.

Thanks!