Just curious, before the surgery, what did the vet tell you he saw from the x-ray?
On the x-ray before the first surgery, the vet showed me a shadow near the bottom of the stomach. He was mainly looking to see if the cat swallowed a string that was constricting the intestines.
He performed exploratory surgery and the intestines were good. That’s when he removed the mass of hair. The cat was vomiting everything (food, water) but couldn’t bring up the hairball.
Today, a different vet showed us a similar shadow on the xray (not identical, just similar). He’s certain it’s the same problem, but they want to keep him overnight before cutting.
Get a new vet. If he found a "shadow", meaning some kind of mass, he should have had a biopsy done, as well as a blood panel to determine which numbers were off, if any.
Those combined will allow the vet to make an "it could be this, or could be that", somewhat of a diagnosis.
I'm only saying this because I just went through it. I found, well was referred to the best vet in the whole world! I am thankful everyday I found him.
The 1st vet I took her to didn't even bother to misdiagnose her, let alone diagnose her.
He wanted to do about $3000 worth of "vitamin testing". What an a-hole.