Oh gosh...I'd take him back to the vet, or to a new vet asap. When a dog stops eating, or hardly eats and suddenly is very low energy -- something is wrong.
What tests did the vet do last week to determine he was fine?
Please take his foam pillows away from him right away, he shouldn't be eating the foam. Did you tell the vet he was eating the foam? Eating foam and other non-food things is sometimes a sign of "pica". Here are some links to read about it:
Pica in Dogs - Page 1 Pica in Dogs - VetInfo