After a little asprin and sugar water she is eating a ton, which makes me think it is a vitamin deficiency. She's been eating and is able to move the leg a little more. After about 30 minutes of gorging on mealworms she stood for a couple seconds on her own! I'm almost certain it's a vitamin deficiency.
Well, I hope you are right. Truth is I had Marek's and the ONLY symptom we had was the leg. I supported with vitamins because I to HOPED it was just a deficiency. The bird ate veraciously! Did not appear to be in pain. Some people are able to help their bird return to full function with vitamin support and a sling to keep the bird elevated where they can put some weight when they desire. It usually takes weeks to months for that to happen. I saved that bird. It seemed like it would make a recovery, aside from the paralysis. But after 2 weeks of caring for a crippled bird, I decided to cull even though the bird was clearly living. That wasn't quality of life for the 9 (now 11) week old chick or myself. It was one of my emotionally hardest culls ever.

Two weeks later, ANOTHER chick started limping. No fooling around! I provide good nutrition and I don't diminish it with treats. I breed my birds and expect healthy and strong quality. If a bird IS suffering nutrient deficiency and I can clearly see it isn't being bullied and kept away from food, then that bird has issues and I don't want it bred forward. Yes I keep them as both pets and livestock. With Mareks being spread by dander and such I do NOT invite it to live among my flock. I culled that second chick on day 2 of limping without sign of in jury. It seems like a hard core farmer mentality and it took me along time to get where I can make hard decisions without second guessing or beating myself up. At this point the good of the entire flock is at stake compared to one bird. It isn't a fun choice but it's the right choice (for me), and the lesser of the evils.
Guess what, as heartbreaking as Marek's is... it can even be in NPIP flocks and is NOT part of their testing. Nor are they required to report it or tell you.

It is a false sense of security for some, but still does test for really important thing like AI, salmonella, and others.
In one post you say you are using aspirin, but the other says advil. Aspirin is useful, advil not so much... is my current understanding.
By the time you can tell a chicken is in pain it is often much worse than you realize. They are prey animals and as such will HIDE anything as long as they possibly can. Otherwise they become an easy target and yes other birds in the flock will notice and take advantage as a mean of elevating their position in the pecking order. Or even peck to death maybe even cannibalize as a means of keeping disease away and the flock strong. Nature is brutal.

Although I do understand the idea that the relief created by the med might create enough relief to eat as you note. And eating does seem to help give the energy to recover... in the medical profession, they very often will not administer any pain meds until they can determine the cause of the pain, Otherwise you are just masking symptoms and making it harder to find the root source. Note that even if you bird does recover doesn't mean it wasn't Marek's. Many have had success with specific vitamin concoctions that include lots of C, and ??, I wish I could remember but I will post later if I find it. Maybe the bird is a survivor! If it does survive you may have no way of knowing which it was until another bird presents with it. Which could happen within a couple weeks or not for years.
Please understand that in no way do I intend to be discouraging or fear mongering. I am only sharing information that is from my experience for informational purposes and each case WILL be different.
With having eaten that many meal worms, I would expect some really nasty poo.

But also suggest you have some sort of grit available to help with digestion.
Hoping for a strong recovery for your chick!
