You initially described some classical symptoms of peripheral neuropathy. I'm not sure about the mouth sore, but the disorder Burning Mouth Syndrome has recently been shown to be associated with certain types of peripheral neuropathy as well(Google "Burning mouth Lauria"). Intraepidermal nerve fiber density testing is currently the gold standard for diagnosing this frustrating disorder. Short of visiting a Mayo clinic in person, consider asking your GP about submitting a skin biopsy sample for ENFD testing. **
Best,
Chris