Thanks for writing to us.
Canker sores usually occurs due to -poor oral hygiene
,vitamin deficiencies,stress etc.
Apply topical steroid
on the affected area.
Lips are stinging due to the ulceration.
Avoid spicy foods.
Maintain oral care.
Vitamin becosules,iron supplements
has to be administered.
Sensitivity while putting pressure on tooth using tongue can be due to-exposed pulp due to decay,attrition,erosion etc.
Get a thorough clinical evaluation by a dentist
Infected pulp has to be removed and restored.