Hi,
Have you tried the Nutro Puppy food? My puppy LOVES it...and she is a very picky eater. Oddly, she doesn't like the Nutro Ultra puppy, just the regular Nutro puppy (green label on can.) She loves it and since it is moist I don't have to worry too much about her water intake. I highly recommend you head out and get some and give it a try. Make sure you warm it up a little before she gets it.
I'm hoping your sweetie perks up soon. Hang in there and keep us posted.
Sophie sends puppy hugs your way....