We just switched Lunas food from what the breeder was feeding her, Purina Puppy Chow (yuck) to Blue Buffalo. We did it so today the first day she got 3/4 Puppy Chow and 1/4 Blue Buffalo. She started it last night and today again for breakfast and lunch. At first her BMs were solid and now it's diarrhea. She also didn't want to eat dinner tonight. But she went to a new pet sitter today while we were out of the house so i'm not sure if it's nerves. Should I continue feeding her the mix but reduce the Blue Buffalo and add it slower? Or give up entirely? If give up what are some suggestions on food?

Diarrhea is normal when switching. Likely will happen with any food u begin to change to.

From my experience with Elara, some kibbles just didn't agree with her. I would always switch foods cold turkey (I know some people are against that, but I've had good luck that way). I found one food that just would not agree with her even though it was pretty healthy. I just switched until I found one she did better on. But I did have Siku would can eat just about anything (stomach of steel!) and could finish off the bags of food Elara couldn't.

With that one food, she had diarrhea immediately. I tried for a few more days with no luck. Then switched to another and no more diarrhea! Then I tested just to see and fed her the old food one night and the diarrhea started again. I just avoid that brand now. BTW, it wasn't buffalo blue. I wasn't trying to hint at that. lol. I've never actually tried that with my girls. I feed mainly Acana now.

I'm just mostly concerned with the fact that she doesn't want to eat her food, she only ate a few kibbles for dinner.

It could be either or. I would back up. Get her BMs solid again, then try switching more slowly (literally just a few kibbles of the new stuff at a time). If she has diarrhea again, then you can probably safely assume it's the food and try another brand.

Food toleration and switching is honestly trial and error. There's no blanket formula.