What is your location in the world? How is the swelling today? The generic name for Benadryl is diphenhydramine. It usually comes in 25 mg tablets, and I would use 1/2 tablet for a 5 pound chicken. Tylosin or Tylan is an antibiotic for treatment of MG (mycoplasma.) I think that others have used the 10% enrofloxacin as well. Dosage for that would be 0.25 ml twice a day for 5 days. It is one of the best antibiotics for gram positive and gram negative bacteria. Doxycycline and oxytetracycline are others use. Coryza tends to be beater treated with sulfa antibiotics.