Hock walking

Hi, I seem to be asking lots of advice at the moment.
I got some battery hens about 2 weeks ago. I had a couple of soft eggs but that cleared up. One of them developed a prolapse that seemed to go after 24 hours and then came back couple of days later. I pushed it back in but it came out again the moment I put her back on the ground.
It was gone again the next day and has not come back since. She no longer has a read behind and looks pretty normal. BUT she is doing this very strange walk. She wals on her hocks and she ducks her head down so she is almost head down bum up.
He feet are looking normal and not clenched closed.
Does anyone have any ideas on what it could be?
Thanks in advance