I very much agree with @aart to clean that out. You may find that is the source of the swelling on the other side. Those nooks/crannies can accumulate quite a bit of crud that festers in there.
For example look at this thread and the photos in the following link, looking at the top of the...
Well isn't she just a cutie!
So she's going broody on you. Most hens will molt or partially molt after being broody and they normally don't lay while molting, so that is what's taking so long it would seem. I do agree with you though, she may live longer with not laying so many eggs a year...
Do you have photos of her too? Does she molt for the whole summer and then lay through winter?
What do you feed her?
The cut on the bottom of the foot looks like it's healing. In the crease, is there something there too?
You can try the Clear Iodine to see if it helps. If it doesn't, then...