"Corrupt files" building up taking all 12 g of my memory after being restored

ive looked and it up and multiple people have the problem of their memory being taken up by a mystery thing people say it's corrupt files and you just need to back up your phone then restore it to factory settings then restore the backup....welllll I've done this multiple times and the problem just wont go away i see it eating my storage away right after I fix it. I'm on iPhone 5s iOS 9.2.1