Looks like plantar pododermatitis. Sometimes its called bumblefoot. It should be treated because it spread into the bones and surrounding tissue. I think its treated with Verimicyn and if a scabbed abcess occurs you might have to cut out the scab. Don't put any topical ointment on your chicken that ends in "caine" like lidocaine or benzocaine. They can cause heart failure in chickens. I don't know how to post links but you can search "bumblefoot in chickens" and pull up alot of pictures and info for treatment. Hope your chickie gets better quickly.