Welcome to BYC! Glad you decided to join our flock. X2 on looking like fowlpox. TwoCrows has given you the links to get help. Please feel free to ask any other questions you may have. We are here to help in any way we can. I hope your hen recovers. Good luck.
Maybe I'm reading this information incorrectly. I can vaccinate if they're not sick and younger than 10 weeks but after that point it must run it's course?
Yes, once they have it, it is too late to vaccinate. You might want to do some asking around in our emergency section. I have never vaccinated against fowl pox, so I am just not sure.
I agree with the other posters--it looks like your hen has Fowl Pox. Fortunately, the disease isn't usually fatal, and your bird should recover in 2-6 weeks on her own.