How to remove Other on iPhone 4S?

Recently (past couple months), my iPhone has been saying I don't have enough space to take even one photo. I backed everything up on my computer and then deleted half my photos and music. Same problem, "Not enough space." So I checked to see what was taking up so much space, and on iTunes it says "Other" is taking up all the space. I did a search and found that Other contains caches and texts, so I deleted a huge amount of old messages, and emptied the Safari cache. Still no luck. So I checked here and people said do a full restore. As of 20 minutes ago, I updated to new software and did a full factory restore. Now about half the "Other" is gone, but there's still 4.5 gb of it. How can I get rid of this?

Sidenote:
I read a while ago that if you have songs from places like youtubetomp3 it can sometimes cause corrupted files and take up space. Seeing as I only had two out of hundreds of songs, and now all music is off the iPhone entirely, I doubt this is what caused the problem in the first place.

If you were jailbroken Cydia uses memory as "Other" as well as jailbreak apps but a restore should have fixed the problem. I would talk to Apple to see what the problem is just don't tell the, you jailbroke your phone (if you did) and hopefully they can fix it.