"Exotic" pet vets are really hard to come by in our area. A co-worker of mine went to Dr. Mandel's in Cleveland Heights (216-321-6040) and had a good experience there. He also has an office in Wickliffe now. I believe it's called the Wickliffe Animal Hospital (440 516-0000). You can also try the Pet Hospital of Willoughby (440 942-8181). They have someone there that does guinea pigs. My husband used to take his dog there (when he had one) and has taken one of our cats there. They are good. The Petsmart in Willoughby has a doctor that sees guinea pigs too, but I've never taken any piggies there.
Honestly I have never taken my piggies in to see a vet. I did call around because one had lice, but I knew for sure it was lice and read (one guinealynx.com) how to treat, so I did it myself. The vets I listed charge like $35-$37 just for the office visit. Check out guinealynx and if it is mites, you probably will have to take your piggie in. Hope this helped!