Take Syrup containing Sucralfate and Oxetacaine 1 tsf teaspoons thrice daily, about an hour after meals, Cap. containing Probiotics once daily . for 3 days atleast.
Will need to know more history to prescribe other medications.
Next Steps
Your blister in the mouth needs to be examined.
Health Tips
Drink lot of water and take more of green leafy vegetables and fruits. Take small but frequent meals. Avoid spicy food, tea and coffee.