Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for difficulty breathing, throat or tongue swelling, faintness, or an inability to swallow saliva.
Contact the treating clinician sooner if symptoms change significantly, a new medicine appears to worsen the burning, or treatment causes troublesome side effects.
A repeat examination is appropriate if a sore, lump, bleeding area, or red or white patch develops, especially if it does not heal within about two weeks.
Seek prompt care for fever, spreading swelling, inability to drink, or substantial unintended weight loss.
And for anyone, someone who:
Routine follow-up allows the clinician to review test results, monitor symptoms, and assess whether treatment is helping.
Because improvement may be slow, it can be useful to track pain intensity, sleep, eating, and daily function rather than focusing only on whether burning has disappeared completely.
Every sign above is quoted from the sofidex article on Burning mouth syndrome. If you are not sure, err upward — it is always reasonable to be checked.