Oh my gosh, poor Little Moe and you's.
You don't think he could have ate some of the sponge and now it's like getting bigger inside him? I know you've spent a lot of money already but it's so sad to say, it oviously hasn't helped him.
I think he needs an x-ray and blood work like others have said. I would be so mad at that vet. Please take him to another vet, he still needs help.