Cornell may take emergencies. If you left now, you might get there in time, otherwise you will end up somewhere local again. This place is supposed to be good, but I don't know how close it is to you:
Animal Medical Center - New York City They may not be great with shunts either.
My guess is that a scintography would have to be done to r/o shunt not just a look at the liver, but could be totally wrong. While they are removing the probable stones, they can get a liver biopsy if you want, but dogs can have both LS and MVD, so having MVD doesn't r/e LS.
It would be nice of your vet to refund what they did today b/c they knew darn well that if he got stones again, they wouldn't be able to see them. So unless they contrasted the xray somehow, I'd be upset.
Hopefully he is just inflamed, but it is more likely another stone or sludge.