Sleeping propped up is helpful with the thick gunk. Many of us have gone thru the same thing and slept in recliners or propped up on extra pillows.

You are correct, rads is still working so thats why it looks worse in your husbands mouth. Dont be afraid to take him back to the doctor if he is still struggling. Too often when a patient ends rads, they feel abandoned by their medical team. At the very least they can suction out the gunky mucous and at the least confirm everything really is ok.

Hang in there! Very soon your husband will begin to improve! Please dont forget to make some time for yourself thru all this too. You are right there every step of the way and going thru it too.