We needed a female chicken for companion to our other female after rooster was killed, didn't want another rooster, anyway, we went to a local weekend selling place (where we think pretty much all ducks/chickens were for meat) and brought home a basic white chicken. The problem is we think she was probably in a cramped cage her entire life, with no space to move around. She hardly moves around and when she does she looks like an overweight old woman when she walks. When she is sitting down one of her legs sticks out to the side, completely out from under her, it almost seems like she probably sat that way in the cage as she grew and now her leg has matured in a wrong position. What we're wondering is if there's anything we can do to help her get better mobility and use of that leg. She can use the leg, it does work, but not to it's full ability and correctly. I can post a pic if that would help. There might not be anything we can do for her except TLC but I just thought I'd see if anyone had any ideas.
It sounds like you bought a cornish cross. They've been so heavily bred for meat that they gain weight extremely fast and often have problems walking. They're not really meant to be kept for eggs/pets. I would eat that one and get a laying breed hen instead.