I'm sorry that your baby is suffering, as are you
I went through this same thing with my first Yorkie, Starr. She had all the same symptoms, same meds, xrays, all that, a whole week of vet visits trying to figure out what was wrong. Xrays showed nothing. Then the vet did a barium series on her and found the blockage. I went home and searched the house that day and found pieces of a colored pencil that she had chewed up and must have eaten some pieces of. Told the vet and he said no wonder it didn't show up, a regular lead pencil would have though, because of the lead in it(metal). So that's probably why there's nothing on your darling's xrays, the earplug was plastic and that won't show up on a regular xray. The movement, or lack of movement, of the barium will help the vet to see a blockage if there is one.
I hope that your little one is all better very very soon. Please keep us posted
