I just saw your post. Almost certainly a slipped tendon. Those can be so hard to treat and they often keep popping out even when you get it back in. It is almost a miracle when you can 'fix' one! One of mine had this when I got her from the feedstore, joint infected and all. Once the joint is infected, it is really impossible to treat I think. The bone basically deteriorates. My vet presented me with either the solution to cull, or to amputate. I did have her leg amputated, and she is a year old now. With that said, I do not think I would do that again. She is waited on hand and foot, but really can't get along well. Her remaining leg became deformed so she cannot stand, but rather flops around or balances with her wings. She can fly a bit. Kind of like a plane bumping on the ground, but never really taking off.
I have to carry her back into the coop each night should she go out during the day because she can't get up any ramp or steps. She can't roost and prefers to sleep in a soft cube at night or get under things where she feels safe. I have to be very careful who she lives with because she is so fragile. She has a new friend now that has a deformed foot and only one layer of skin on her leg 9no scales) who has taken up with her. They are quite sweet together. She has to eat out of a plate because it is low to the ground. I try to make her life as pleasant as I can while she is with us. Her picture is in the Online Poultry Show under Ameraucanas, her name is Hoppi.
You did the right thing even though I know it seems hard.