If PG or VG is causing some kind of reaction, then 100% juice in either should allow you to compare. If it's a flavoring, then unflavored PG or VG juice would be in order for the test.
Some juices contain PGA (pure grain alcohol) which can be drying to oral and nasal tissues. The first thing I'd do is make sure that I was hydrated. Dehydration of oral and nasal tissues can cause some symptoms, too. Describe your symptoms and someone will pick up on what might be causing them. Vaping in general can dry your mouth, since PG is a humectant that absorbs moisture and incorporates it into the vapor you exhale. Each hit can take a little moisture as the droplets contact moisture in your mouth.