Please visit a dentist so that they can see the sore and discuss your oral habits etc to make a diagnosis. Avoid smoking and hot foods in the meantime. Dont delay as it is already 2 months since your ulcer/sore appeared. The dentist will check and guide you accordingly.
Next Steps
Avoid any irritants like hot food, smoking, tobacco etc.
Health Tips
2 months of delay in showing to dentist is not good