Hi.. Thanks for the query.. Your symptoms are pointing towards Apthous ulcers that in common are known as Canker sores.. They occur in different locations in mouth like inner cheeks, inner lips, tongue, palate etc.. Causes can be nutritional deficiencies, eating very sour, spicy or hot foods, digestive disturbances, acid reflux etc.. So my suggestion is to start gargling with a solution of milk of magnesia and benadryl.. Do warm saline gargles.. Take Vitamin B complex supplements.. Gargle with numbing mouthwash containing Lidocaine.. If there is no improvement then get evaluated by an Oral Physician.. Hope this helps.. Regards..