I'd leave off the penicillin...it's not doing anything at all because the legs are not infected, merely inflamed. I'd soak it in warm epsom salts a few times a week(no scrubbing..a gentle, massaging type soak and wash, gentle patting dry), reapply the castor oil each time...not with a toothbrush, as the brushing merely irritates the tissues. Just a goodly amount massaged gently into the feet and then leave it alone. When it's been let get that bad, it takes some recovery time. Just be patient and monitor progress...but too much fooling with the feet, scrubbing, washing, etc. will only deplete the natural oils, cause irritation to the already compromised tissue underneath and around the scales, and wash off the castor oil...and that needs to stay in place.
Meanwhile, if the birds are walking around on wet, muddy, barren run soils or even dusty, dry, barren run soils, I'd change that to a soft, absorbent deep litter system that will promote good bacterial cultures in the run. This will keep the feet cleaner, less prone to staying wet and muddy, and will help the overall bird health.