Hello:
There is also a stress related condition called "burning mouth syndrome." I have seen a few cases of it.
Typically people complain of a burning on the cheeks, lips, gums or tongue. There is not usually any physical changes that can be detected. The condition can be very painful. Canker sores are common with it due to the stress from the condition.
If that is the problem it is treated with viscous lidocaine 2%. This is swished in the mouth to numb the area. A doctor may also prescribe a medication called an SSRI which does help in many cases. This condition is usually self limiting and clears up on its own. It is a tough one to diagnose since there are not changes in the oral mucousa.
Canker sore are stress activated when the bodies immune systems becomes weakened. They are very painful.
A trip to the family doctor would be a good place to start. Best of luck.