minecraft not saving all progress made during last play

explored while making a map during game of minecraft... saved and quit. When I re-entered the game, my map was still drawn but all of the items I had collected while making it weren't saved. The iron golum and arrows I crafted were gone. I have also had other issues lately, like being inside walls when I re-enter a game, if I have recently dug into cobblestone. I saw a reported bug similar to this that was refused because it was modded minecraft, but mine is unmodded.