I agree with Tony, get your dog to a vet ASAP.
My dog is being treated for worms (hook and tape) and after speaking with our vet, she warned us that if the dogs belly becomes bloated, it could be ringworm. The problem with worms is they are very tough to get rid of. It may require a few treatments.
Hi. Gastric dilatation and volvulus (GDV) can be fatal to a dog within hours, so get your dog back to the vet straight away. This may not be the problem, but if it is, then it's an emergency. Another possible cause of stomach swelling in dogs is peritonitis. This serious infection is usually caused by puncture or rupture of your dog's stomach or intestine, due to splinters from a bone, ulcers, tumors, or other causes. Peritonitis can also occur if the gallbladder or urinary bladder ruptures. Again, this need immediate diagnosis and treatment.
The hookworm diagnosis is also relevant, because there is trauma and blood loss with hookworm infestation. This could cause the swollen stomach, particularly if there has been some internal injury and rupture as a result. If you have been trying to overfeed your dog (there is usually massive weight loss with hookworm), then this could also have caused bloat - this is also a very serious and potentially fatal condition.
What I am saying then is get your dog to a vet now, don't wait.
Tony