So I restored my jailbroken iPhone 4 from a backup and after that I have 3.5 gb of other when I check the storage. I think it might have something to do with SwapTunes.
How do I fix this?
All iOS devices build up "Other" over time and jailbreaking your device usually speeds up the pace of the build up. The only way to get rid of 95% of the "Other" (you can't get rid of it all) would be to restore and set up as new.