Congrats on the great improvements!!! Eating a whopper meal is quite an accomplishment!!! So glad you posted this as it helps others who have recently finished.
The tightness in your neck muscles and jaws needs to be addressed. You will need PT exercises to work these muscles. Massages and stretching will help so keep working those muscles. On your next check up discuss these things with your doc and ask about seeing a PT.
Thyroid is another issue many of us deal with after rads. This should be brought up with your ENT on the next visit, but dont put it off too long. If you dont have an appointment within the next month, make on to get this checked out. Many of us have our thyroid fried and end up taking lifelong thyroid meds (myself included).
Your improvements will continue over the next year. Keep up the great progress