Okay, just completed some more intensive research. And judging my hen compared to other cases and studies, she either isn't showing infectious signs, or she is going to be a "survivor" of a Marek's infection. But most likely, she's simply not displaying symptoms of an infection.
Once such study that supported this was
found here.
"An acute phase of the disease can be seen within 72-96 hours where the lymphoid system, primarily bursa and thymus, undergoes cytolytic changes. Infected birds normally recover from the acute phase of the infection after 6-7 days and become latent."
Other sites state that in the nerve infections, the paralysis phase lasts 1-2 days in
recurring instances, or it kills them completely within a week. Furthermore, they state that leg paralysis affects the ENTIRE leg, as swelling of the sciatic nerve is the cause of such paralysis.
"Babygirl" as she has been named since this began, isn't showing any signs of complete leg paralysis. It's JUST her foot. More than that, it's just her TOES. But since the main pad of her foot is swollen right now, it makes complete sense that she would have some numbness in her toes.
Also, the swelling in her foot is NOT tumorous. I know because I saw fluid there (visible between her toes), poked it, and yellow/clear liquid came out, like pus. That further supports either a local infection (she does not have bumblefoot though and I see no cuts or abrasions) or a local injury. And I'm guessing that if her leg were paralyzed and she ALSO had something wrong with her foot, blood flow would probably be affected enough NOT to allow swelling.
She does have a problem with some feather shafts. But that was an after-effect of releasing her in the backyard the first day. She wanted to be back in the safety of the pen so bad, and with a hurt foot, she quite literally tripped herself a couple of times and bent a feather UNDER the skin's surface. (I later yanked the feather, and the follicle appears fine.) She also stands on the one good foot absolutely fine. And she CAN walk on the bad foot, but I can tell it's painful. It looks more like it's just a bad limp though, not a paralyzed foot. She doesn't drag the entire leg along. She moves it forward just fine. She simply doesn't spread her toes before setting it down, and sometimes steps ON the ends of her toes (steps down while toes are still folded/curled).
Once I compared all of this to Marek's, I realized she's just walking in a very protected manner from the pain. Imagine a cut on your palm or smashing your hand with a hammer, and then walking on hands and knees. You'd probably walk with your fist balled up - similar to what she is doing with her toes.
But more importantly, she's getting better. VERY slowly, but she is. The first day I had her inside all day, she did not want to put any weight on the foot. Now she does, but very gingerly. She really only folds her toes and gets tripped up when she walks across a rumple in the blanket. And I will admit that she does indeed tend to have one wing drooping. But I know that isn't from being paralyzed or numb (she snatches it back when I try to fold it against her back - so I know she can feel it) - it's for balance as she keeps her weight off of the one bad foot. When she's laying down, it's folded like normal.
Now whatever happened to the bad foot, I'm not sure. I know it isn't broken - at least no compound fractures. I pulled, tugged, twisted (lightly), and bent her leg and foot to look for one, but felt nothing out of place. But if it was a sprain, I thought she would feel much better by now. Maybe it's the fact that she actually is still putting weight on it (she pitched a fit in the sling like Granny Clampett with a shotgun) and it's healing slowly because of the usage. Or maybe chickens take MUCH longer to heal from a sprain than humans, dogs, or cats. Either way, I'm really starting to think Marek's isn't the problem here. Or at the very least, it's not a problem anymore.