I have a baby shihtzu that is 5 1/2 months old. She used to love to eat and get excited for every meal, but she began to throw up occasionally and for the past week has refused to eat. She has only once actually gone to her bowl to eat, and will only eat small amounts from our hands, but that's even if she does. Most of the time she will come to us as if she wants to eat but will smell the food seem like she feels sick or nauseous and turn away. She hardly has any energy anymore and is getting very thin. We have taken her to the vet and they have to force feed her food there and when she comes home, she still won't eat.
If anyone knows of what might be wrong with my puppy, or just any suggestions or anything, my family and I would greatly appreciate it.

I have no idea, have you tried changing foods, could it be an allergic reaction to the food she is eating?

Did the vet run any tests or just force feed her? I would take her back to the vet, or a different vet, and have some tests done, obviously something isn't right.

For now try mushing up her food with a bit of warm water or milk and hand feeding her or syringe feeding her, anything to get some nutrients in. If she isn't drinking well then pedialyte (infant rehydration drink) is good and full of electrolytes that will get her hydrated.

I don't know what else to tell you, I hope that everything works out.

Take care.