I got my answer on the imunity. Thank you for the links. I am calmed down now. I will keep an eye on them, will check their throats and put Neosporin on anything, that looks painful (I have bought Neosporin recently anyways, because I stepped on a nail and about inch and a half went in my foot)
That bump on the side of her beak does not look like fowl pox. In my opinion... Make sure the others don't start developing this. I think it's best that you separate her until you find our what is wrong with her and how to treat this.
It could turn out to be a fatal disease and I'm sure you wouldn't want all of your hens passing away from it.
Don't be too worried, I doubt it is anything that is transmissible to humans. I still think it is fowl pox. Just try to keep us updated and post pictures of any new bumps. Best of luck with your hen!