Our 11 year old boston has developed a sore on the back corner of her lips / mouth. Over the past few days it has become more swollen and she continues to rub and scratch it and is now it is swollen to the size of my adult thumb and firm. When it first started, we had taken her to the vet and they suggested that it was just from rubbing and nothing to worry about. She is now lethargic. We have a appt with the vet again tomorrow afternoon.Has anyone experienced anything like this?