Hello,
Are you using a
UVB light at all? The Sun Glo basking bulb is not a
UVB light just a basking light so your dragon is most likely going to be having some metabolic bone issues right now. The swelling of the leg is indicative of that, or of an injury due to weak bones.
My suggestion is to get a
UVB light such as the Reptisun 10 flourescent tube light or a Mercury vapor bulb such as the Megaray or a T-rex active UV heat. Since your tank is large enough, then you can use a mercury vapor lamp. I see you are in the UK, so a good flourescent tube bulb you can get there is the Arcadia D3 12%.
Unfortunately, even with you giving calcium without UVB exposure he cannot absorb his calcium without UVB exposure. He cannot synthesize D3 either, which help keep his bones strong as well.
Keep us posted on how he is doing.
Tracie