The cause is a fairly rare but could allow is due to friction, due to our mouths too dry

When you're chewing, gigimu once in a while will be touching the wall in pipimu, because the walls in pipimu is the make of your food remains in the zone of the cud. Your tongue is also occasionally will move past between the two rahangmu because your tongue is memindah-mindahkan the position of food in your mouth. This can all happen smoothly due to the slippery mouth conditions due to salivary gland liurmu produced water.
The natural lubrication is necessary in order for the process to chew your food well. However, the process to chew can experience problems because it can fuck up the lubrication dries up. Yes, your lips can dry out in the Middle you are eating. Especially if you eat the food absorbing moisture in large quantities such as bread, cake, fried foods and other foods that are hydrophobic. If the food is dry and oily at the same time, you will quickly make your mouth dry. This is what is causing you pain when gigimu mengatup clamping tongue in cheek or wall.