Can you please start a thread of your own along with information and photos?
This way you'll get some suggestions suited to your situation and pullet.
This thread is close to a year old and the original poster that you are asking questions hasn't been on in about the same amount of time.
Thanks!
Do you have any photos you wish to share?
It's odd for one that old to develop splayed leg overnight. Do you feel any swelling of joints or are the joints turned at all?
She may be suffering from a leg bone deformity, hard to really tell.
If she were to stand up, is the leg twisted or is the joint pointing outward?
Vitamins that contain B2 (Riboflavin) wouldn't hurt. You can give her 1/4 tablet B-Complex once a day for a few weeks.