I am new to quail, so I am open to suggestions. I have serama, finches, parakeets. Daughter has a dove, I just Love small birds and have been researching quail. There are so many kinds I see, what have you got? They would be strictly pets at my house.
Please try again to spread apart the webbing between the toes on the underside of the foot. With the swelling it can be hard to do, so maybe try to insert a qtip in the creases to see if you get any "crud"
Check the deep webbing between the toes. Could be a crud ball has developed and you can push it out from the top. Tends to come back if that's what it is, so check feet often.
This could be a crud ball. Look carefully on the underside in the webbing between the toes. Dirt & fecal matter can collect and form a stone like ball that continues to collect in the webbing.
Are the birds sitting directly under the lamp? If they are too close, their feathers are being burned off. Too hot, feathers are getting brittle and break off.