Dermatitis in Chickens

Dermatitis in Chickens - Holly

I have noticed flaky, dry skin on the right hand side of Holly's head and around her right ear.  There is a little on her left side but it's minimal.  She's not scratching, yawning constantly or rubbing her head so it's not uncomfortable for her.  I was a little worried it may be mites but as there was very little dry build up in her ear, the dryness was restricted to one side and no scratching, it seemed very unlikely. None of the other girls were exhibiting the same issue either and mites are usually really catching.   
The Vet felt that it was likely to be dermatitis or similar.  Possibly due to a vitamin deficiency (zinc perhaps) so gave Holly an injection to counteract this and said I should see a difference in 5 days or so.  He said although it may be due to a reaction with something from her environment, it would seem unlikely, as what would she be in contact with which just touched the right side of her head and not the rest of her?  Confident me agreed wholeheartedly and as Holly is in no pain, I was not too worried for her.  
So the next morning I was in the pen with her and I picked her up and to give her an encouraging cuddle.  I was dotting kisses on the right side of her head and telling her how sweet she was when it hit me - I was kissing the right side of her head!  I always kiss the right side of her head.  Me, smothered in lip balm.  I'm a cosmetic testing monster.  
I have checked Holly's head today, four days after the visit and her face certainly has a lot less dry patches.  At this point I don't know if it's just a coincidence, the injection or the kissing removal. 
So Holly is now kiss free.  Well, I do admit to eying off her wing as a future site of affection.  This morning I found Holly napping on the sand in the pen.  Everyone else who was out (Holly's sister Alice was on the nest working on an egg) was preening all around her and she was snoozing away with her head under her wing.  Hens sleeping with their head under their wing, especially out in the open when they're healthy and well, is very unusual. 
 

Holly - Sunday 18th May 2013.  Sleeping soundly. 

Holly, being watched over by Jewel.