You are probably suffering from what is known as burning tongue syndrome or burning mouth syndrome. As the names indicate, the condition usually affects the tongue, but can also affect the lips, the palate, the gums, and the cheeks. The cause is not fully understood — possibilities include menopause, diabetes, nutritional deficiencies, medications, and bacterial or fungal infection of the skin. As a result, treating the condition is also difficult.
However, if you can figure out what immediately causes or aggravates the sensation, you can start to address the problem. Try to make a note of whether your toothpaste, a chewing gum, certain spices or foods, certain juices, tobacco or anything else has an effect on your tongue. If so, try to find a replacement.
Another possibility is “geographic tongue”. The condition is harmless, and usually manifests itself in the form of discoloured, map shaped patches on the tongue. In some people, this may be accompanied by a burning sensation. Again, the cause of this condition is not clear, but you can try to avoid consuming substances that aggravate the burning.
Since you have already tried medication for thrush, also known as candidiasis, we can most probably rule this out. However, self medication does not always work, so you should visit a doctor for a diagnosis.
answered by G M