iPhone Storage Issue

Hi, my iphone has started sending me notifications telling me that my storage is full, with my ability to use whatsapp and the camera halted, however, when I check my storage status on settings, it says I have only filled 46.7 of 64gb.

Additionally, I estimate about 20gb of this to be filled by 'other' files,

Is this a glitch in my storage whereby I have actually almost filled my iphone and the status bar is incorrect, or that I haven't filled my iphone but it thinks it is full?

Also, does anybody know what this 'other' files business is about?

Many Thanks,

Elliot