I had my wisdom teeth taken out in January and had no problems until about a month or so ago. I developed a hard lump about the size of a marble on my gums on the back right side of my mouth. It did not hurt or bother me and I thought it would go away. It is still there and now it is started to feel sore. I went to my dentist at home and he did an x-ray and found nothing. I have an appointment with my oral surgeon pending as of now. What could this be?!?