It seems that you may be having aphthous ulcers
on the inner part of palate..roof of mouth. It may be due to some cause or idiopathic..that is without cause.
,vitamin deficiencies,infections anywhere in body,trauma,HIV,drugs..etc you consult dermatologist
or oral surgeon.you may be investigated to find out some cause. And then the is treated.apply triamcinolone
1 % paint or glycerin. Do betadine gargles. Vtamin B complex,folic acid,iron..may be taken. Immunoboosters like levamisole 50 mg daily.
You may be alright.
Dr. Ilyas Patel MD