Hen having trouble walking

[ChikNLovr]

Cookie, my 20 month old Speckled Sussex is not looking good. Unlike the rest of the flock, she didn't seem to come out of her fall moult. Her comb is still pale and she just hasn't looked too good.
Now, in the last week she is having trouble walking. She is slow and has to plop down to rest frequently. Her steps are very awkward. And today she was unable to hop the 12" to go out the run gate with the rest of the flock. She clearly wanted to but just wasn't up to the effort, so she turned away and just sat down.
I picked her up 2 days ago to feel all over, hoping that I would find a painful leg or some sort of injury. Nothing. And her vent is clean and doesn't look swollen.
I'm afraid she is taking a slow path to demise. Any suggestions or thoughts on what might be going on?

 

[Eggcessive]

These types of problems are difficult to diagnose. Since she recently molted that could have added to her problem. Was she vaccinated for Mareks disease? Has she lost weight? Hens with internal laying or egg yolk peritonitis can have problems walking. Does she have any swelling of her leg joints, or signs of bumblefoot on the bottoms of her feet? Can you put her on some poultry vitamins in her water or food?

 

[ChikNLovr]

Thanks for your assistance. The feed store where I picked up the chicks claims they were vaccinated for Mareks. I don't know how much she weighed previously, but she certainly felt quite lightweight when I picked her up the other day. I didn't notice any leg swelling, and I poked around her feet. Though I didn't know about Bumblefoot, so I will go check her feet again tomorrow. I am happy to try vitamins and will figure out how to isolate her to make sure she is the one consuming the vitamins. Any particular type of vitamins?
Any other thoughts?

 

[seminolewind]

This has worked for me a few times I've used it. First I worm with Valbazen. Then I treat with sulfadimethoxine and Tylan or any 'cillin antibiotic for a week. That will solve 99% of chicken problems. Other problems could be an egg that's stuck, internal laying, Marek's, or something you may not solve.