poorly pheasant - 'thickened leg'

[hattie]

Can anyone help our black pheasant, returned after absence of about a month... Beautiful large male aged 11months has limp and swelling at top of both 'shanks' - top of leg where scales meet feathers. Both legs affected although visably limping only on one. swelling is dry, non reddened - looks almost like excessive scale growth - does not look like leg mite, scales lower down leg and feet look fine. Eating well and certainly can fly (somewhat aggressively (or perhaps over affectionately!) at our other pheasant who is also an 11month old male - but golden).
Pheasant is totally free range, living in farming countryside so I don't think it's the result of a traffic injury.
Think he has returned for TLC so would love to be able to do something for him (medicine in drinking water?!) Can't catch him - easily...
Many thanks.