I know some people do not like to jump to the Marek's conclusion to quickly, but from reading what I have read so far, I am thinking it sounds very similar to the symptoms we saw, and it was diagnosed as Marek's by an avian vet.
I am no expert on the disease, but we have had it here. They can present as these kinds of symptoms at a varying age range, sometimes in the 6-10 week range at the easiest, but also just before or just after they begin to lay. I have read it is often triggered by stress when the immune system is most vulnerable. It can also be present with no sign until the bird is in it's 'old age'.
My amateur advice would be to separate any birds showing signs and keep the food and water up to them. (Transmission in the flock is almost unavoidable at this point if it is MD, but you don't want any healthy birds picking on sick birds)
I would continue to monitor symptoms and research what you see. If it is MD, some birds have recovered to live on, some have natural immunity and unfortunately, some will die. I would strongly advise if possible to have a necropsy done if a bird does die. Here, they can be done for free at a specialist (via a vet appointment) if it is suspected of ding of a transmittable disease. You may find the same there. Once you know for sure if you have it or not, you can take measures to manage what ever has caused your birds to get ill.
Outside the Marek's Disease box, some things to consider.
Have they been wormed?
Were they vaccinated?
Did you home hatch or purchase live birds?
Have you brought an new birds to your flock?
I am no expert on the disease, but we have had it here. They can present as these kinds of symptoms at a varying age range, sometimes in the 6-10 week range at the easiest, but also just before or just after they begin to lay. I have read it is often triggered by stress when the immune system is most vulnerable. It can also be present with no sign until the bird is in it's 'old age'.
My amateur advice would be to separate any birds showing signs and keep the food and water up to them. (Transmission in the flock is almost unavoidable at this point if it is MD, but you don't want any healthy birds picking on sick birds)
I would continue to monitor symptoms and research what you see. If it is MD, some birds have recovered to live on, some have natural immunity and unfortunately, some will die. I would strongly advise if possible to have a necropsy done if a bird does die. Here, they can be done for free at a specialist (via a vet appointment) if it is suspected of ding of a transmittable disease. You may find the same there. Once you know for sure if you have it or not, you can take measures to manage what ever has caused your birds to get ill.
Outside the Marek's Disease box, some things to consider.
Have they been wormed?
Were they vaccinated?
Did you home hatch or purchase live birds?
Have you brought an new birds to your flock?