Ok so I had 7 chickens mixed breeds (I'm a beginner) I had 2 polands, 3 warrens and 2 sussex. 2 weeks ago one of the polish became ill and passed away the same day. 2 days ago the 2nd polish became ill and also passed the same day. They where supposedly around 6 months old however they where laying every day since day 1 of having them, I know polands aren't very good layers but these two gave us at least 6 eggs each every week I thought we just had a good pair! With both dying so close together I now presume that the seller has lied about the age and that they are older birds. The 3 warrens and 2 Sussex however have grown and only started laying around 2 months ago so I know these where young hens. Since the first death eggs hit an extremely low of only 1 a day. I found that I had a very bad mite problem. They where everywhere!! They are also moulting, so I have been today and spent £50 on mite powder for the birds, a mite spray for the coop and run, and a vitamin boost for the water. When I got to them this morning I noticed one of the warrens where acting alike the two that died, very slow movements and keeping to herself. It is wierd they are there usual selves but then suddenly the next day become dopey and rapidly down hill from there until 8-12 hrs later when they die. The warren that is not her self today does have abit of fight in her as she seems to be walking around occasionally, I have also seen a big lump of feathers been plucked from her neck. I have treated everywhere for mite, and the birds. They now have there vitamin supplement and everything has been thouroughly cleaned. Is there any more I can do??