He needs to be tubed fluids, ASAP! Then once hydrated he needs food tubed. To quote my vet "it's not usually the disease that kills them, it's dehydration and starvation".
-Kathy
The Plumb's book says that it's 100mg/kg for Turkeys and to use cautiously in small birds due to procaine toxicity.
This link also has dosing info:
http://avianmedicine.net/content/uploads/2013/03/09_therapeutic_agents.pdf
-Kathy
No need to shout, and sorry if you think I was picking on you, that was not my intent. FWIW, I doubt any amount of penicillin would have resolved the pus, but that's just been my experience.
-Kathy
Isn't this the chicken that's getting Cipro? If so, do not give any other medications. @Wayne&Kim1963 , read post #54, pus removal has already been discussed.
-Kathy
FYI it's been my experience that unless you remove the pus, antibiotics won't work, the pus will keep the area from healing, Here is a skull picture, it might help you do your surgery. It's not a chicken, but it should work.
-Kathy