Appetite stimulant for 5 month old Puppy ?

We adopted a 5 month old Miniature Dachshund about 2 weeks ago. She was doing great and suddenly, yesterday, she stopped eating. She ignored her kibble and I tried enticing her with boiled chicken and hamburger meat. She just turned her head away. I called my vet and she said to bring her in early. Right before bedtime she about about 20 pieces of kibble. This morning we went to the vet. Her stool is firm and parasite free, she's up to date on vaccines,her CBC is normal and sh'e running around playing and barking. The vet couldn't find anything wrong so she gave her medication for gastritis and said that she was just very picky. To entice her with other foods and some dogs just eat very little. Has anyone had a pup that ate like this. What is a good appetite stimulant?