could be just the moulting, but watch out for the pecking order,
the lowest in the rank sometimes get pecked by the others.
this happened to ours when we first got our chucks.
we brought the one who was been pecked out of the run,
and into our house for the night!!!!.
late next day we put her back in,prob sorted.
hope its just the moulting process, but if they are getting pecked by the others,
might be best to put them else where for a while.
good luck