New and sneezing!

Hello all! i have just joined the forum and got my first chickens a week ago.

I may be beeing over protective here, but just in case its something to nip in the bud...

My two hens started sneezing yesterday, they also scratch around their faces and the feathers on the backs of their necks have gone limp - kind of like unwashed hair.
One, chloe, has a blue tinge to her wattle, nearest the skin tho, not the tip and it has been fading back to red.

They both have tail and neck feathers missing as they were raised with cockrels, but i have looked them over and can't find any mites on their necks.

They are about 20 wks old, and i feed them wet layers (they wouldn't even consider them dry and didnt eat for two days.) i put mite powder in the coup, dust bath of sand and put cider vinegar in their water.

Is there anything i should worry about?
have i done all neccessary?
done something i shouldn't?

its all a lot to take in!

any input would be much appreciated!

Hi
I would Frontline and Flubenvet your girls asap, just so that you know were you are with them. 
They could be sneezing because their coop is dusty from the mite powder.
Good luck and as hen maiden says i'm sure you will get lots more advice.