Thanks for the picture. I agree with Wyorp Rock that the bubbles in the eye are probably mycoplasma (MG) and related to the the bump. It cause sinus infection and conjunctivitis. Both Denagard (Tiamulin, TiaGard) and Tylsoin are common antibiotics that treat symptoms of an outbreak. Since it is a chronic disease, the whole flock may be carriers, and none should be rehomed or sold. MG can be common in backyard flocks, and there can be outbreaks during times of stress, especially during a molt or cold weather. I would close the flock for the lives of all of the chickens. Once all are gone, you can get healthy chicks from a hatchery after waiting a few weeks. No need to cull your flock.
