gecko mouth

Question
my leopard gecko has come weird crust on the side of his
mouth and in the inside. i have read other things that say
it is mouth rot and it could cause death! i have had him
for 5 years. i have been watch it for a week now and have
NO idea what it is!!!     please tell me what to do

Answer
Hello Noah,

It sounds like your leopard gecko does have mouthrot or he has retained shed.  Is that a possibility perhaps?
What is the humidity in the tank?  Do you you have a moist humid hide?  
Did he injure his mouth in any way to cause a sore that is infected?
What do you keep the temperatures in there?
What does the inside of his mouth look like?

Tracie