If injecting drugs into a chicken, there is less chances of hitting a nerve in the breast muscle. Some will also inject under the skin in the back of the neck. Have you noticed if she has a bad odor to her head? If so, I would probably change to a sulfa drug like Di-Methox or Sulmet in the water.
Tylan Soluble Powder is water soluble, and Tylan50 injection is given by some people orally, but it works best as a shot into the breast muscle. Gallimycin (erythromycin) is also a good water soluble treatment. I just looked up the Neochlor--it will treat CRD and E.Coli, so you can try it for a...
It looks like a respiratory infection such as mycoplasma gallisepticum (MG or CRD) or coryza. They will cause swelling of the sinuses. There are others depending on symptoms. What antibiotic are you using? Tylosin (Tylan), erythromycin (Gallimycin), and tetracycline are used to treat MG...