Hi,
I had a similar problem. Almost half of my storage was Documents and Data, and no way of knowing what this related to specifically. This was about 20GB!
I decided to try to resolve, so before doing anything, I backed up my phone on iCloud.
I connected the phone to my mac and observed the memory usage bar like you show above. The phone was completely choked with data.
I don't know about you, but I have played candy crush in the past and I reached level 1,000, before giving up this dreadful addiction. Anyway, I couldn't understand how I was able to play any level of candy crush at any time, but the iPhone suggests this app only took up about 300mb. So I removed candy crush from my phone using the Apps page in itunes. Instantly, my docs and data usage fell by about a quarter. I freed up about 4GB! This must have been candy crush data.
Next, I deleted all my versions of Angry birds. Removal of Angry Birds (originals) and Angry Birds Seasons freed up space again.
So my theory was that all the apps save game data in this section on the phone.
However, its no good removing these apps if you use them a lot.
So what I did next was reset my phone to factory settings, and then restore from my iCloud back up.
Still updating the Apps, but the amount of storage used for Documents and Data is now only 1.5GB, and, yes, Candy Crush has loaded and still starts up at level 1000.
It also looks like the amount of space used by Apps in total has fallen too.
So that could be the solution. Back up and restart the phone from factory settings. Give your self 3-4 hours to do this properly. Updating the apps is taking ages today, because my BB is down to about 10mbps, rather than the normal 25.
I'll update when the phone is completely finished updating apps and I have reloaded my music.
