My blackie, Boo, is thin and I can feel his bones, too, but I had his senior blood work done not too long ago and he's fine, just in advanced years; he's 18. Your vet told you, however, that Woobie has some liver function problem, so I'd say that it's good that you're having him checked again. I don't have any suggestions for you, just prayers that all will go well. Please keep us posted.