My Russian tortoise's mouth has both of the sides of it "eroded". I will try to get some pictures soon, but it makes it that he can't eat his lettuce. I have no idea how this happened, I haven't changed his diet or anything. His beak looks like any normal Russian beak, but the sides of his mouth look eroded like I said. I have no idea what to do about this. Is it common? Have anybody had any experience with this?