I currently have fowlpox in my flock! Mostly everyone's recovered greatly but 3-4 still have it but it's getting better. I say let them be, the truth is they are probably now all infected but it takes time to start showing signs. If it's the dry kind give them nutri drench and alot of vitimans to help combat it. There is no cure. Make sure they're all eating everyday. Healthy chickens will survive it. Thankfully all my chickens are very healthy so they all took it extremely well. If you chickens look weak take them to the vet! Good luck and sorry if this wasn't much help