Poor vegas hope he's feeling better soon.
It reminds me of my last cocker girl who sufferred from pancreatitis a couple of times, the symptoms are very similar, the first time she got it she was hunched up and her tummy was hard to touch, she was also vomiting but the vets thought it was a tummy bug, eventully she was diagnosed with pancreatitis and spent 3 days on a drip in the vets, she bounced back from that episode and was fed on a prescription diet for a couple of years, the second time she got it she was very lethargic and just led on the floor refusing to move i knew instantly it was pancreatitis again and took her straight to the vets who took bloods to confirm it was pancreatits and started her on antibiotics immediatly she was very poorly for a few days as she also suffered from epilepsy and so had quite a few fits over this time as well. She did bounce back All I know is the earlier they are diagnosed, antibiotics given and food withdrawn the better.