my hens are looking dejected

I have 3 Buff orpington hens about 14 weeks old, 2 of them are very dejected looking, standing all hunched up. The 3rd is running around the run as usual. I was told it might be coiccidosis (not sure of spelling) and have treated with Coxoid which seem ed to perk them up at first but now they look so mournful. They are drinking but don't seem much interested in food! Any suggestions please?

Buforp

Have you tried giving them Apple Cider Vinegar in the water?
I find with Orpingtons and Cochins, this time of year when the nights are drawing in they look a bit sorry for themselves    ACV seems to help. I gave my Cochins some of this a few weeks ago as they where going through an early moult and the three oldest hens are looking great and just started laying again 

Michelle xx

It is a 7 day course and they are at the end, should I keep giving it to them? They do look a bit better today - eating the sweetcorn I have given them.
I will also try the cider apple vinegar, what proportions?
Thanks for replies