A second opinion is always a good idea anyhow for something so serious, so I wouldn't waste any time finding another vet. In the meantime, continue w/his medication and we'll do our part by praying that Jack responds to it. This is so scary and frustrating, I know. Our furkids can't talk and tell us what's wrong or what hurts and sometimes we have to trust our instincts. Hang in there and please keep us posted.