With Herm being on the bottom of the pecking order, the original incident probably happened like this: one chicken pecked Herm's comb as a normal warning, but drew blood in the process, causing the attacker and the others to go into a blood frenzy (then is when chickens see blood and start attacking because they want to have a pecking order punching bag and they want to drink blood), getting Herm beat up. Your most recent update says that it happened again, and I am sorry! It happened again this time probably because of the same thing I already explained. Her flockmates will continue using her as a pecking order punching bag unless she is separated.