I hope this answer is helpful.
We appreciate you reaching out to us. Vomiting that lasts more than 3 days is most likely something is wrong with your pet. Diseases, metabolic disorders, digestive system disorders, drug side effects, altered food intake, infections, etc. may be suspected.
Make sure to drink plenty of water and fast for 24 hours. After fasting, give the feed little by little. Persistent and severe vomiting after fasting has a poor prognosis. In this case, it is best to visit a veterinarian. If the vomiting shows relief and no other symptoms, your pet may be able to recover on its own.
If you have any further questions please ask us. Thank you.

My dog hasn’t been eating the past few days. When he does eat, it’s just a little bit and he throws up later.

He won’t eat and when he does eat he throws up a little.