Bid the vet do an x-ray to rule out a blockage? It sounds like she is experiencing pain.
Meanwhile, I might soak the kibble in water overnight, maybe mix it with a little wet food or cooked chopped up chicken or lean meat. Maybe add a splash of water to her meals (many dogs do not consume enough water), only feed twice a day.
My dog that has a sensitive stomach does well on Nutrisca Salmon and Chickpea as a base.
Check Chewy.com for prices.
PS: Brush the teeth every evening, check youtube for how to videos, small breeds have lousy teeth.
