Help with checking if player is moving

Before anyone says this is a duplicate post, I just want to clear something up. I know how to check if the player is moving or not, but I'm a little confused as to how to check if the player has moved to a different BLOCK, not just that the player is moving. I'm trying to recreate the video that TapL made, where when you earn every block you walk on. I recommend watching the video to understand what I am trying to recreate. This is what I have so far, but the problem is that it gives me way too many blocks and it glitches out whenever I try to place a block. It also sometimes randomly clears my inventory.