Its not a sudden issue, she has always had it (whatever it is), but today it got bad. Thank you for responding and sorry about your hen!She's limping the same way as a hen I used to have that always ran a little funny but as she grew bigger the limp got worse and worse.
If it's a sudden issue though, a daily 1/2 of a baby aspirin for a few days is magic if a hen has a minor sprain or something. Not so much for long-term issues.
Good luck and best wishes.
Edit: I don't know if my hen had something neurological or a deformity or something, but I always thought she was maybe a twin chick and it could've been due to a deformity before hatching as she always had a slight limp even as a little chick.