You may want to check her daily to ensure her crop has food/water before she goes to roost - that she's been eating.
Check her frequently for lice/mites as well.
Just monitor her - she may need extra help or supportive care from you to make it through.
Sorry to hear you are having problems.
It's a good idea to get testing to make sure what you are dealing with is Marek's.
You can look up your state lab HERE
Some folks get testing through a private lab like THIS and THIS
Birds can "recover" become asymptomatic, but may relapse - hard to...