24 Hens and only 2 eggs a day!!!!!!!

Hey ya'll. We need some insight. Since my last posting, everything was going quite well. We increased our flock a couple of times and the girls were doing great. They are now free-ranging on about 2 acres. They have an automatic feeder with Dumor Layer/Breeder Crumble always available to supplement. Up until about 2½ months ago we were getting 7 to 10 eggs a day out of our (7) Black Sex Links, (4) Buff Orpingtons and (3) Americanas. Then all of a sudden they just quit laying. We might get 1 or 2 a day. We decided to get (10) Hy-Line Browns (pullets). The pullets are now of laying age and a couple of them have started laying smallish dark brown shelled eggs, so we know they are coming from the Hy-lines. But now the older girls have completely quit laying. the Sex Links we know are all at least 4 to 5 years old so they may be done laying completely (understandable) but the Orpingtons and the Americanas are only a little over a year old. We did notice some worms in some droppings so we have wormed them. Then we noticed that a couple were digging and pecking themselves. So we sprayed all of them down with a solution to rid them of mites and other critters. We try to keep dimatacious earth (food grade) on the floor of the coop, laying boxes, and the stalls where they regularly like to dust bath. In the last 2 weeks since the worming and spraying, none of them seem to be digging and pecking themselves anymore, we have not noticed any more worms in their droppings. But still no eggs. Anyone have any ideas. We really don't want to have to go buy eggs and we refuse to go to the grocery store and buy those nasty disgusting tings they try to pass off as eggs.