You bring back memories I try to forget. I remember the throat pain and the hour to get down 6 oz of liquid. Had to wait for my pain meds. to kick in before I attempted to swallow. I used over the counter laxitives as well. Sometimes they worked and sometimes not. Sometimes I resorted to OTC enemas and that usually helped.
My pain and therefore need for pain meds lasted for a 2-3 months post radiation. Pin meds lead to constipation. As I my throat healed and I gradually got into to more soups, ability to drink, and increase in energy, the constipation problem passed as well. You will get better, 1 day at a time, keep moving.