We have something similar going on with one of our hens. Can't find any specific injury but did find mites. Treated for mites, gave liquamycin, and soaked wing in Epsom salts and warm water.
My daughter's EE hen's wing was droopy about a week ago. Upon further examination we found a nasty infected lump under her wing. We also found mites while checking her over. We tried to find the site of any injury and found none. We treated her for mites with Ivermectin and gave her three doses...
