[Q] Phone Storage Full... but WHY? topic

I recently received a phone storage full notification on my HTC One Mini, which surprised me because I don't have a ton of apps (mostly stock ones that came with the phone), and less than a gig of music, plus 3 gigs of photos/videos. I checked the "storage" calculator under settings and it showed the various categories that are taking up the most space (e.g. apps/music/photos/downloads/other). What I discovered was that "other" was consuming over 5 gigs of my storage space! I plugged my phone into the computer and started navigating through all the folders on the phone and can't seem to find the culprit.

What could it be?

I deleted all but my most important text messages (that barely made a dent in the storage), cleared my browser cache (still did very little), and now I don't know where else to look. Any suggestions/thoughts?