Why is the dog vomiting and having diarrhea?

Vomiting and diarrhea can come from eating bad food or a bacterial or viral gut infection. If a dog eats too much at once or consumes rotten food, it can develop indigestion and gut flora imbalance, leading to vomiting, diarrhea, and abdominal pain. Stop feeding temporarily, and after vomiting eases, give pet probiotics to settle the stomach, then slowly return to a bland diet.

If a bacterial or viral infection causes acute gastroenteritis, the dog will also vomit and have diarrhea. Have a vet run a virus test; if viral infection is ruled out, treat with anti-inflammatory, anti-emetic, and gut-repair medications.