Hey! Fellow Portlander!
It could be a previous bumblefoot (they can happen in the toes too) that exploded up and down, and those are the scars - or it closed up and was still infected inside.
It could also be an old injury where the hen stepped on something that went THROUGH her foot - from the pictures, that occurred to me. There doesn't seem to be any issue with the pad of her foot- just that odd spot on the heel that seems to extend up to that weird spot by her toes.
I'd go with a good Epsom salt soak- then you can kinda play with it and see if it loosens. If you do the PRID, it will need to be wrapped. What that does is gets any infection to come to a point near the skin so it can be removed.
I've definitely seen PRID at Walmart- just look online and see if your nearest store sells it. Pick up some gauze (narrow kind) and some "no-stick" pads which will be for after it opens up - that's where you'll pack it with Neosporin, cover the hole (but not putting the gauze into the hole- just the Neosporin) then gauze, then vetwrap--
I love having small Fiskar curved scissors - makes it SO much easier to change the bandages because the blade faces away from the leg but they're still nice and sharp and easy to control.
https://www.walmart.com/ip/Fiskars-4-Orange-Curved-Scissors-Right-Left-Handed-Use/34932916
I like to have the saline wound-cleaner that comes in a blue bottle for flushing things once they've been opened up --- and at either Wilco or Coastal you'll find vetwrap if you don't have some.
Choose a boring color of vetwrap so the other chickens leave it alone. No red or pink.
Cut Vetwrap into 3/4"-1" wide strips that are around 12-15" long un-stretched- this takes very sharp scissors, so if you don't have any, I would buy a pair.
OK- if you're using PRID, apply with gloves to both sides of the weird areas- then apply gauze. To keep a "boot" on the foot, you'll kinda paper-mache the vetwrap on. I usually start with a couple of wraps around her lower leg, then I start working in between the toes and over the bottom pad and so-on. I usually use 3-5 strips before it's all said and done, with care that it's not too tight- give it a day or two, unwrap, have another look - feel free to wash it, soak with Epsom salts again-- see if anything looks like it's starting to swell up to the surface if you used the PRID. That's what it's supposed to do.
Hopefully just having it wrapped will help her mobility.