Q: Macbook Air hard drive space unaccounted for

I noticed that free hard drive space on my Macbook Air was rapidly disappearing even though I had not been adding much in new files, certainly not enough to account for the 10s of gigabytes that have disappeared in the last week. I cleaned it out of unnecessary media files, giving it another 20 gb of space. The status bar reflected it accurately at first, but when I started up the computer this morning, it had lost 30 gb from that adjustment.

After running WhatSize and DaisyDisk, I see that they both claim that my Air is using 296 gb, which is in agreement with About This Mac, but when you look at the actual folder sizes, there is no way what they measure adds up to that amount.

Using Get Info, I got the following measurements:

Applications 14.43 gb

Users 42.45

System 7.77

Library 8.95

That all adds up to roughly 74 gb of space being used. WhatSize actually gives me different numbers. Where in the world are the other 220 or so missing gbs? Any help would be greatly appreciated.

(Note: Even as I have typed this out, I notice that about 8 gbs of free space have disappeared in the Status Bar)

Here are some screenshots of WhatSize and Disk Utility. DU claims that "Other" takes up 283 gb, but I can't figure out what is included in whatever it is measuring as "Other."