We have a jersey giant who has the same issues down to the time line. Everyone said all of the same above on different forums.
We ended up taking her to a vet, things hadn't gotten worse but nothing had changed.
Vet said she was healthy and not in pain, just cannot put her feet flat. Because...
We have a big girl with same systems, same timing. Took her in to a vet after a picking issue (the way she sits her but is in the air, and she has a odd vent, so the other chickens pecked it) the vet said she was born with feet that don't allow her to open them all the way. Because of it her...