Moulting or something else?

I have checked/searched other topics and been unable to come to a conclusive desicion.  

My Welsumer hen is currently looking a bit under the weather and loosing feathers.  Where I do appreciate that chooks moult do they look miserable whilst going through the process?

She doesn't seem as lively as normal and the colour seems to have gone from her comb, shes using the nest box at night rather than roosting and seems to snooze in the run during the day.  But she is eating and drinking.  

Any thoughts and ideas would be appreciated

Thanks

Claire