Triton bewitch leaking?

Hi I recently changed the head of our triton shower and a few days later I was in the shower when all of a sudden water started pouring out from where the hose attaches to the outlet pipe and bearly any water coming from
The actual head of the shower. I have read a few reviews and can't work out whether its more likely to be the PRD or a fault with the actual outlet pipe.

Any ideas how to check for faults? I took the shower cover off and I'm unsure if I have located the PRD but all washers/rings seem to be in place.

Any help would be much appreciated.

Thanks