One Plus X, camera will not open, how do I fix it?

A

AC Question

I've had a One Plus X for nearly 6 months now and I have only recently been experiencing issues with it. Ever since upgrading to Marshmallow 6.0.1 my phone has become slightly slower, however the main issue I face is inability to use my camera. It works neither on the camera app or on third party apps such as snapchat. I have tried downgrading software, but to no avail. I have cleared my cache. The only way it works is when I restart my phone, but only lasts a few photos before saying it is not working again.
Please can someone help me fix this?