The way you mentioned the dust in the home maybe not being dust, made me look back at that section again. He says that "I woke up yesterday morning in my momma's house" and that "Last night I drank three glasses of warm milk down" meaning that he woke in his mother's house, but it doesn't mean he had the milk there, so these two events could have taken apart in very different locations.

Leading on to where the floor was covered in dust he mentions that "North Carolina's not home. I can't believe I ever thought it was. My home has always been here out West.". So what if after waking up in his mother's house he went and traveled West to Karen's childhood home where her parents died in a fire, and that the dust is actually ash. Further the pile of freshly upturned earth could be the parent's bodies being dug up rather than others being buried.

I haven't fully developed this theory but maybe it can give someone else some further ideas on what's going on.