It really sucks to go to several vets, but sometimes it's necessary to find a good one. I could go to all the vets in this town and none of them would be that knowledgeable. I have to drive 45 min away to go to my normal vet, who is great.
Before you go you could try talking to some vets on the phone and see how they sound. See if they sound like they have an idea about what's going on and what kind of tests they would plan on administering, then you could check back with us if you want. That way you don't have to spend the money going to several and figuring out which one will be the best bet. Obviously they can't diagnose over the phone, but you can get a pretty good feel for how they are and whether they have more ideas than the vets you've already been to.