Oh Sheryl I am so sorry you and Benji are having to go through this. My condolences on the loss of Peanut. I know you have been to the Doctor and Benji the vet but was the vet a skin specialists? If not I would recommend Benji be checked out. I would also bring in samples of the specks. Also I would recommend taking Benji to a veterinary dentist to see what they think is going on with Benji's teeth. Regardless I would go to a second Vet. If Peanut passed from similar symptoms and the Vet is not sure what caused it you need to find someone who will. Here are some sites to check out I hope they help. Best wishes to you and Benji.
About.com: http://www.vetmed.vt.edu/ Ryan-VHUP Google maryland veterinary dermatology - Google Search