We are typically quite sloppy about what are physical sensations and what are mental sensations (memories, mental images, and mental impressions of other sensations). These two kinds of sensations actually oscillate back and forth, a back and forth interplay, one arising and passing and then the other arising and passing, in a somewhat quick but quite penetrable fashion. Being clear about exactly when the physical sensations are there will begin to clarify their slippery counterpart that helps create the illusion of continuity or solidity: flickering mental impressions.
