How is he today?
When the stomach is bloated like that and they are lethargic, it is probably best to pull food (if the dog is big enough) unless they are really hungry. Yogurt might settle the stomach (or might not) but beyond that it would seem that adding more could make the problem worse.
When you can't get him to drink you can syringe Pedialyte or Pediasure.
Gastric Dilatation-Volvulus is severe bloat with the stomach turning. It is extremely dangerous but not common in small dogs. Usually with this the dog will be in severe pain, trying to throw up but can't, making weird noses and restless.
Bloat (Gastric Dilatation and Volvulus) in Dogs