Why has my disk usage gone dramatically higher?

Have you looked in iTunes?

When the iPad is connected, iTunes shows the disk usage in a linear graphic bar at the bottom of the window. They're color coded and labeled Audio, Video, Apps, etc, with a gray section for free space. Hovering your cursor over each segment reveals the data size and number of items for the segment.

Perhaps keeping an eye on this would help identify what's suddenly bloated.

How much space is your Other using? You may be able to reduce.

How Do I Get Rid Of The “Other” Data Stored On My iPad Or iPhone?

http://tinyurl.com/85w6xwn

With an iOS device, the “Other” space in iTunes is used to store things like documents, settings, caches, and a few other important items. If you sync lots of documents to apps like GoodReader, DropCopy, or anything else that reads external files, your storage use can skyrocket. With iOS 5/6, you can see exactly which applications are taking up the most space. Just head to Settings > General > Usage, and tap the button labeled Show All Apps. The storage section will show you the app and how much storage space it is taking up. Tap on the app name to get a description of the additional storage space being used by the app’s documents and data. You can remove the storage-hogging application and all of its data directly from this screen, or manually remove the data by opening the app. Some applications, especially those designed by Apple, will allow you to remove stored data by swiping from left to right on the item to reveal a Delete button.

 Cheers, Tom 😉