I have crps and my foot changes to a beautiful blue and swells when I'm sitting. When I raise it, the nice pink color returns. My PM said that is typical with crps. Educate yourself as much as possible. Read everything you can about crps/rsd. Hope you don't have it and it's great that your doctor is ruling out everything else like peripheral neuropathy, diabetes, nerve entrapment. With crps, alot of the diagnosis is ruling everything else out. Good luck.