It's chronic. What we don't realise is how much the coccyx actually moves. How are your bowels? Constipation won't help.
Every time we breath, move, turn over in bed, sneeze ......... get an inflatable swimming ring rather than what you are using? The wedge may be too solid . How do you lay in bed, maybe a pillow under each bum cheek/thigh to ease the coccyx off the bed.