Hi Wendy,
While I am no expert and Ill let more experienced users comment after myself, the key is that you saw the ENT and he found nothing, nor did the MRI. That is actually really really good news.
What I would recommend doing on your next visit (and this may already be his plan anyway) is to have the node biopsied if this hasnt already been done. This would give a more definitive diagnosis as to what is inside the node itself and could point to any other areas of concern.
I wish you the best of luck!
Ian.