It sounds like you have a communicable disease. It's spreading and rapidly. You may want to isolate all of your hens from each other, at least separate them by age or when you got them. If you introduced some to the others, the older ones may have immunity to whatever it is or may be spreading something to the new gals. You've lost all pullets so it sounds like your hens are fine but your youngins are the ones in trouble. Until you know what it is you can't very well medicate for it. You only mentioned the listlessness. Are you noticing loose or bloody stools, are they having equilibrium problems, panting, anything else unusual?
Unfortunately, once an animal like a chicken (prey) shows signs of disease, it is usually too late to save them (cost effectively) but not too late to save the rest. This is because they don't want to be seen by predators as an easy meal, it's just instinct that they'd hide pain or illness as long as they could from you. Since you've lost 3 and you are very close with your chickens, you may want to seek out your locate farm animal (not cat/dog) vet for guidance. You can contact your state poultry vet for general free council as well. They are very good about working with the backyard raisers as they know that is where most of the disease mysteries reside.
For now an electrolyte or vitamin supplement would help keep the healthy birds energized and full up on vitamins and minerals. It's a way you can help keep their systems working well to help fight off what may be circulating.
Sorry for the long post. As for tilling your soil. There are microbes that you might bring to the surface that would otherwise stay where they are. By shuffling around soil you would possibly expose your chickens to something more. If you think this is a worm or cocci overload you need to medicate properly for that and then move your coop, leaving the pooped out bugs behind. If you worm but don't move the birds you'll get re-ingestion and the cycle continues.
Good Luck!!!
Unfortunately, once an animal like a chicken (prey) shows signs of disease, it is usually too late to save them (cost effectively) but not too late to save the rest. This is because they don't want to be seen by predators as an easy meal, it's just instinct that they'd hide pain or illness as long as they could from you. Since you've lost 3 and you are very close with your chickens, you may want to seek out your locate farm animal (not cat/dog) vet for guidance. You can contact your state poultry vet for general free council as well. They are very good about working with the backyard raisers as they know that is where most of the disease mysteries reside.
For now an electrolyte or vitamin supplement would help keep the healthy birds energized and full up on vitamins and minerals. It's a way you can help keep their systems working well to help fight off what may be circulating.
Sorry for the long post. As for tilling your soil. There are microbes that you might bring to the surface that would otherwise stay where they are. By shuffling around soil you would possibly expose your chickens to something more. If you think this is a worm or cocci overload you need to medicate properly for that and then move your coop, leaving the pooped out bugs behind. If you worm but don't move the birds you'll get re-ingestion and the cycle continues.
Good Luck!!!