not being able to raise it is often an indication of tiredness - like deep exhaustion, so back off till you feel better.
Saw this too late! Gym session went well this morning so I'm hopeful that it was a short term exhaustionfrom a stressful day. Will keep an eye though. Thank you.
A single stressful day shouldn't have this effect on you (unless you are on the edge) - look back at the past week or two and assess what life/training/work stress has been like. Maybe need to revisit aspects of life.