Pic displays it nicely here (https://ibb.co/vZ4hJVr), but this happened after the water had been turned off for some boiler maintenance.
When it was turned back on, I foolishly turned the shower fully on. Cue water pouring from the side/edge/rim of the shower head.
So far I’ve tried ensuring the holes aren’t blocked, taking it off and putting it back on again, and pressing the face/plate of the head firmly.
In case it helps, the shower head is a Triton Isabel 3.