There are many types of sores that can appear anywhere within the mouth, including the inner cheeks, gums, tongue, lips, or palate. Most mouth sores
are cold sores
or fever blisters, canker sores
, or other irritation caused by biting of the cheek, tongue, or lip; braces or burning the mouth from hot food or drinks.
Cold sores are caused by herpes simplex virus and are very contagious. Usually, you have tenderness, tingling, or burning before the actual sore appears.