Injectable Tylan can be given orally at a dosage of 1/4 ml per pound 3 times a day for 5 days. It is not necessary to inject it, and it can cause muscle damage at the injection site. I prefer the oral powder to put in the water if the chicken is drinking normally. Yes, one can use both...
The foamy eye with conjunctivitis could be mycoplasma gallisepticum (MG,) a chronic respiratory disease. I would try to get Tylosin or Tiamulin/Denagard from a vet near you if more serious symptoms or eyelid swelling occur. Those will treat MG. Rinse the eye with sterile saline. Terramycin eye...