There's no treatment. It's a virus transmitted by mosquitoes. It will run it's course in 4-6 weeks. Just make sure those aren't peck wounds. I wouldn't mess with the scabs as they can spread it too.
Be prepared for the rest of your chickens to get it too...it is highly contagious. Here is some good info on it if you'd like to read up on it - http://www.poultrydvm.com/condition/fowl-pox
Thank you for posting this. I think my Cockerel might be getting this also. But he has only just become the only Cockerel I have after a fox attack so I will monitor him and see if it might have been him fighting with the others.