If it is a sudden condition then it's probably Coz of having extreme hot food. If ur facing this problem from more than a month then it can be tongue burning syndrome.. Cause of it can be GERD(gastrointestinal reflux disorder),medications(for
diabetes BP, hypothyroidism), over use of mouthwash or severe brushing etc..
Next Steps
Put cold packs on ur tongue using ice cubes..it will give you symptomatic relief.
Health Tips
Do not eat anything hot.. Avoid carbonated drinks and acidic foods. Discontinue d use of mouthwash if any..