All is not lost even if it is Mareks and it might not be.
Mareks is a virus but not all birds develop symptoms by any means.Certain breeds are notoriously susceptble to it and silkies are the ones that spring to mind.
I had mareks here about 8 or 9 years ago. One day my birds were in fine fettle and the next, one of them would develop a limp of drop a wing. Sometimes it would start to manifest itself in a very mild form with what I would describe as a droopy or lazey eye. The Americans call it Range Paralysis by the way. For some reason, it always seemed to take my very best and quite often a few days before a show as well.
I had two choices to make at this stage. I either innoculated all my chicks at day old, or I could choose to only breed from stock that seemed resistant to it. As I say, the disease only seemed to hit certain strains and i dispensed with these and only kept and bred from the resistant ones. My strategy seems to have worked and although a bit of luck may have been involved, I havent had a case for the last six years.
I was lucky I guess, because even at its worse I only had half a dozen cases a year, I've heard of breeders who suffer far more.
One thing I do recomend is not to mess about with anybirds that you supect of having Mareks. You should simply cull them and dispose of their bodys ASAP. Inspite of what people say, there's no way back from Mareks, if anyone tells you that they've nursed a hen back from Mareks, then take it from me that the bird never had the disease. Its very much a progressive disease.
From what the poster has described, I'm not certain that the bird has the condition. Sometimes the condition comes on very quickly and you may find your bird dead. On other ocaasions it may take a considerable time to run its unavoidable course. The characteristic pose of a bird that has died of Mareks is for it to have one of its legs stuck out rigidly behind it, a wing dropped or both.
You quite obviouly havent put the whole nations health at risk by what you've done in caring for your pet.
but in this case I'd cull the bird and dispose of it.