Weird things happening to my storage.

I was trying to install a game from Steam, but it said, 'Not enough storage.' When I checked, I found that 70GB of my storage was being used by applications. The weird part was that it showed 70GB being used by applications. However, when I manually added up the sizes, the total only came to 57.31GB.

Any guesses as to what is happening?

(side note: when I tried to use get info, it showed only 7GB.Although I already selected all of them.)