I'm sorry that you may be dealing with Marek's.
If possible, it's a good idea to get confirmation testing just to be sure Marek's is the reason for the symptoms you have notice.
Though heartbreaking, Marek's is not always a death sentence and most people manage symptoms as they arise. If...
I would provide her with her normal feed (wet or dry) if she's willing to eat. Bits of eggs is fine too. Provide feed free choice, they will eat or not usually.
I usually make grit available free choice, just a few pieces.
If you are giving flushes, I'd wait until after you finish to deworm...
What is the crop like in the morning after she's had a night's sleep?
You can try the molasses flush and see if that helps push the material out. She needs to consume all of it for it to be effective. Syringe or tube the molasses solution into her if she's not willing to drink it on her own.
I would only give 1 stool softener a day for only 2 days in a row. You can just pop the gel pill right into the beak, there's no need to try to squeeze out the contents into food.
For the molasses flush to work, all of it really needs to be consumed. It's 1tsp Molasses to 1/4 cup water...