Ekim 's Vet visit

As you all know Ekim has been vomiting since he went on a diet and his food was changed. Well we have tried everything to prevent the vomiting but nothing has worked so far. Today we spent most of the morning at the vets. Ekim seems fine temp normal lymph nodes ok, gums pink, blood work fine. Dr thought it could possibly be megaesophagus, so Ekim had some x rays taken and it wasn;t that. All looked normal except for a small shadow that could be indicative of a mass, so Dr decided to perform more x rays but nothing showed up. Thank God. The only problem is that she feels sometimes a mass could be hidden due to the broad chest, so she wants to do an ultrasound later this week. I hope and pray they don't find anything. She sent him home on steroids and pepcid and new food, Prescribtion Z/D, I hate anything by Hills but if it helps I'll try anything. His stomach was clear,kidneys were fine, hips good everything she is just trying to be cautious due to the shadow in the first x ray. As I said it didn't turn up on the additional view  taken with Ekim lying on his on his back. x rays did show some arthritis in his spine, very mild but I will keep an eye on that also. He weighs 87 lbs down from 95 but he has been dieting for the past few months so his weight has stayed the same, so no major weight loss going on despite his once a day vomiting. He may have an irritable bowel so hopefully the meds will help, but this to may warrent further tests such as a biopsy if the vomiting persists. I sure hope we get to the botom of this as I hate to see anything wrong with my baby.