A regular MD may or may not be able to diagnose oral lichen planus, but a rheumatologist should. Dentists and oral hygienists see it quite often, so should be able tell. It's hard for a person to see it on themselves, since it is inside the mouth, but it shows up as lighter colored webbing or lacey looking tissue. Google Images oral lichen planus for pics.

Ask your hygienist or dentist to look for it. They’re probably already aware of it if you have it.