You can give chickens baby aspirin.( 81mg.) I usually give 1/2 tablet crushed in a small amount of water every 4 hours.I've only had to give aspirin to 2 chickens, but both responded well to it.
One of the few things that can slow or stop laying is darkness. This means almost complete darkness. With your hen enjoying being outdoors, this may be difficult. It is also difficult on you. I have seen this suggested with really extreme injuries, with the hen being kept in a dark room like a bathroom, or a closet. With her leg break being so high on the leg, it is easy to see how laying would be painful for her.
Good luck to you and your beautiful Peanut Butter.