Many times a respiratory disease will affect one side of the face and then spread to the other side, since it is a sinus infection as well as conjunctivitis. Then if the infection is still spreading, it can go on to the air sacs. I haven’t seen any pictures of your chicken yet, do you have any of the eyes or face? It does sound like she has coryza, but she also could have mycoplasma (MG) or infectious bronchitis virus as well. The antibiotics I earlier mention to give for MG (Tylosin, Tiamulin, Oxytetracycline) can be combined with sulfa antibiotics (sulfadimethoxine, trimeth sulfa, etc) and given at the same time. Amoxicillin does not treat either disease. Viruses do not respond to antibiotics. If there is swelling of the eyelids or face, pus may need to be squeezed out of the sinus. Here is a graphic video of pus removal from the eye and sinus: