What mite stuff did you get?I've got the mite stuff to put around and on him. We'll do that today.
Do you know what I could put on the cracks on his feet that is safe for chooks?
Scaly Leg Mites live under the scales of the feet/toes, something like a dust or permethrin spray generally will not get rid of SLM. You need to smother them, a link to how to treat was posted previously, but repost/linked below.
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Looks like he has a bad case Scaly Leg Mites which will cause swelling and scabs.
Check him for lice and mites on the body as well.
Here's how to treat the feet.
https://www.backyardchickens.com/articles/treating-scaly-leg-mites-slm-what-you-need-to-know.77376/