This does look like Marek's, sadly. There are, however, other things it CAN be... if you wish to try to help her with the other possible ailments then you can attempt to do so. It's up to you how much time and energy you wish to invest. I have a list of things that look like Marek's here, if you wish to investigate: https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/
Recovery (there is no cure) from Marek's is not common but as Rebrascora said, sometimes they do recover. They often have a suppressed immune system forevermore if they show the ataxia/paralysis and may be more prone to other illnesses such as cocci, etc. Once they go off food, or if they start laboring to breathe, though... it's usually not something they can come back from. Struggling to breathe means that the lymphomas are likely present in the lungs and/or heart and death is very likely.
Recovery (there is no cure) from Marek's is not common but as Rebrascora said, sometimes they do recover. They often have a suppressed immune system forevermore if they show the ataxia/paralysis and may be more prone to other illnesses such as cocci, etc. Once they go off food, or if they start laboring to breathe, though... it's usually not something they can come back from. Struggling to breathe means that the lymphomas are likely present in the lungs and/or heart and death is very likely.