I am a cat breeder, so might be able to give you some ideas. It sounds like an obstruction of some kind. Shiny ingested items will NOT show up on x-ray. It could also be that the bowel has telescoped into itself. I would def be taking your cat to another vet and ask them about what I have said. I am very surprised that the first vet didn't want to do exploratory surgery. Both things I listed above can cause death.
Bridgette- 05/93-09/10, Jasmine-01/96-5/06/09, Dakotah-14/12/05, Joshua-31/10/12, Sabrina-1/07/01-26/11/13, Shane 11/09/01-08/22/14, Samantha-07/12/14, Amber, Jody, Wendy, Gabriele-01/23/12-12/21/13, Kimi, Jakob, Mandy, Abigail, Tanner, Tonya.