I got a Macbook Pro early 2015 and I noticed my available storage space has decreased by 5-7 GB over the last few weeks even if I did not install or save anything new on it. How is that possible? Also, if I look at the storage allocation in "About my mac" I see that over 3GB is taken by pictures, but all my pictures are on an external drive, I counted the space taken by the odd pictures physically on the laptop and it is less than 100MB. I tried re-indexing the drive (or whatever it is called) but things did not change. Any clue what is happening? Thanks!