I had a problem last year with two of my chickens, which my vet said was Fowl Pox. I sadly lost the two of them, one to Dry Pox and one suddenly to Wet Pox. I thought to begin with, that she just had a chest infection, causing her to cough. I couldn't get her in with my Vet, so had to take her to a different practice, who didnt even look down her throat. They gave her a shot of antibiotics but sadly she died that evening. The Dry Pox started with yellow lumps on her wattles and comb, which from the photos, you'll see, over the weeks, got worse, causing areas all over body to react, including her legs and feathers. She also tested positive for ringworm, so I too was treating her for a fungal infection as well as letting the Fowl Pox take its course.
The latter pictures is where I had, out of desperation, used Gentian Violets. She sadly gave up her fight after 4 weeks and died in my arms
Her Fowl Pox looks different to most of the pictures on here?
Good luck, to anyone whose chickens are fighting this horrible disease. I did isolate this hen from my others and fortunately, it didn't spread any further.
I still haven't got over losing my beautiful girls.