There can be so many reasons for the sore tongue. You may have to diagnose the reasons for it.
You have to seek doctor’s help if it persists long.
Some of the reasons include:
1.      Emotional Stress.
2.      Dehydration.
3.      Vitamins Deficiency like B12.
4.      Sometimes teeth start getting sharp and hurt the tongue and can cause ulcers.
5.      Biting the tongue.
6.      Food Allergies.
7.      Allergies to Tooth Pastes, Mouth wash and Chewing gums.
8.      Anemia/ Iron deficiency.
1.      First of all reduce the caffeine intake.
2.      Gargle with warm salt water at least 3 times a day.
3.      Take lots of water.
4.      Take vitamin(B12) with Doctor’s suggestion.
5.      Intake of tomatoes juice.
6.      Avoid Spicy food.
7.      Take milk with ½ spoon turmeric powder.