Apthous ulcers are of three types: Minor (Mikulicz), Major (Sutton's) and Herpetiform (viral/clustered/snail-track ulcers).
Causes include stress, acidity, acid reflux
, trauma, food allergies, certain foods (citrus, milk), Vitamin deficiency
(esp. B complex), Iron, Folic acid
, Zinc deficiency
. Rarely hormonal changes may have a link. Even rarer is lupus and Behcet's Syndrome
. Have you changed any food/ cooking oil or new toothpaste?
Local treatment includes liquid Glycerin IP or commercially available ointments like Zytee, Smyle, Orasep, 5% amlexanox (Lexanox) and others.
A mouthwash may be used. The above deficiencies must be corrected. Acid reflux must be controlled, if present. You may also try Tab. Rebagen (rebamipide) 100 mg t.d.s. for a week.