iPhone 6 says there are 0kb of available space, it won't back up on the computer or iCloud, and the apps keep crashing.

Hi Apple Community, this iPhone 6 16GBs is only 2 months old or so, and it seems that every unsolved problem is happening. Even though there appear to be 1.83GB free on the phone itself, it won't let me take any pictures, download any updates, scroll very far into apps like Tumblr and Facebook, and in the General --> About, it says there are 0kb available, I've deleted numerous apps, and this has not changed. I followed the directions to Backup and then Restore or update my phone, but it won't let me fully Sync or Backup the iPhone on iTunes. I tried an iCloud Backup, and the progress bar for the Backup has not moved in hours, and no "Estimated Time Remaining" has come up.

I'm not sure what to do, my next step will be calling Apple if no solutions can come from this. Can anyone help?