i have a small flock only 8 hens, two of the hens have lost the feathers on their necks and they dont seem to be growing back, i do not have a rooster so they arent pecked and i have not seen the other hens picking on them either..they are both 2 years old were in full feather before this and the rest of the hens are in full feather, i have powdered them for lice and they have been dewormed... they both seem very healthy other than this and they are both laying... any thoughts or suggestions? thanks