Do you know how old she is?
If she is having trouble walking I am guessing she has one of these three diseases:
-Bumblefoot: Signs of this are pussy, infected areas on the foot pads spreading up the foot
-Infectious Synovitis: Where the feet are excessive swollen and they are unable to walk...
I would check for two things. Look to see if her foot pads are inflamed and pussy, if so, she has bumblefoot. Also, check her feet for Infectious Synovitis, which is where the legs are very swollen and the bird cannot walk. I'm guessing it's either those, or Marek's Disease.