Sophie,
Sorry to hear things are going a little ruff. As far as the thick mucus, I would wash mouth out with warm water mixed with salt & soda. It helps cut it. Also keep eye out for mouth thrush.
Most of us that had radiation lost the thyroid. I was 4 months out and found out Thyroid was not working. Now on Medication for it for life.
Even though your husband has feeding tube, please make sure he swallows water everyday to help keep his throat open.
After the saliva glands stop over working, he will get dry mouth. Then you will need other products to help with that. Most of us here use the biotene products. Oral Balance for dry mouth.
Take care of your self as well. You need to rest when you can. Take a nap when your husband is sleeping.
Things will slowly get better. Hang in there. Tell your Dr. of any problems or concerns you may have. Do not be afraid to ask questions.
Take care,
Diane