Hi my turtle is in a cage like for fish and he has a huge ball on one side of his cheek wondering what it is??? Could u help... is it cause hes growing?????
How big is your tortoise? and how big is the tank? The cause is more then likely from them constantly running into the glass.
They are getting a slight burn from the glass rubbing against them. You may need to possibly take your tortoises for back yard or park trips, in order for them to use most their energy, so they can sleep in their tanks instead of try to escape.
I have heard online, that tortoises don't understand glass. One possible solution was to take a piece of cardboard and tape it along the bottom of the glass so they understand there is a barrier. Have not tried that one myself.