Why does my iPhone keeping saying I have low storage and 0 bytes?!

I keep getting a notification on my iPhone 6 saying I have no storage so I click on the settings option it supplies. When I go onto that it said I have 0 bytes left.

I then thought I would delete a couple of bigger apps such as YouTube and a few more. My next step was to delete half of my photos so now I'm only left with 400. I deleted unnessesarry messages and mail I had. But after doing all of this it still says I have 0 BYTES LEFT!

I've only bought a couple of songs off of iTunes.

It's so frustrating because it keeps crashing my apps and causing them to not work properly. I'm having to constantly restart my phone and even after that sometimes it still don't work. When I'm texting someone the messages start scrabbling up and sometimes vanishing. WHAT SHOULD I DO?! Please help if you can.

Read more: Why does my iPhone keeping saying I have low storage and 0 bytes?!