I had not heard of this until I read your post. I just googled it and I cannot find any way to get this out of your dog other than surgery. As you know it can move to just about any where in the dogs body.
I hope that you do decide to take your dog back to the vet to have this removed. I know it will cost you a lot of money, however when you got the pet that dog became your responsibility to take care of. Please don't just let the dog suffer. The longer your wait the worse it becomes.