If you wished me luck last night, many thanks. It worked.
Took 5mg of oxycodone at 11:30. By 12:30, I felt calm and drowsy, so I went to bed. Lay there restfully, with no problem breathing, but didn’t actually fall asleep. So I took half a milligram of lorazepam, as planned, and that did the job. Comfortable sleep; up at 9, feeling a little bit drowsy –probably a benzo side-effect –but functional. May nap this afternoon. Main thing is that there was no repetition of the breathing difficulty. Dr. Gary Emmett suspects it was a radiation side-effect, and likely to dissipate with time, rather than a drug side-effect.
Voice maybe a little bit better, but still very thin. Turns out that the liquid and the tablets I was advised to get to treat dry mouth do a fairly good job at dealing with the sore throat.