You said

"Show the owner the x-ray and explain about kidney stones and how to treat them."

Nope!  You blew the diagnosis!  Don't feel bad, everyone has missed a diagnosis.  Just learn from it, be humbled by it and try to not rush to a diagnosis in the future.  Being just a little more thorough would have shown you the correct diagnosis.  Good idea to explain the x-rays to the owner but that is not the VERY NEXT thing you should do.

View the diagnosis here or close this window and go back and try your very next move.