I too had this awful problem during radiation treatment.

I slept with pillows propping up my shoulders, head,and neck - almost in a sitting position.

I kept a water bottle by the bed & box of tissues.

I had an prescription for cough syrup with codiene that really helped. I needed it at night and also each day before the radiation treatments because the thick mucus would get stuck/make me cough as I was lying on the radiation table with my faced pinned down in that wonderful form-fitting mask.

I found (and still do) that warm drinks - a weak herbal tea, not too hot helped to thin the junk in my throat. ANd yes, lots of swishing and spitting.

Bear with it. Its rotten but gets bet post-rad.

good luck,
michelle