Hi AndiL76,
What a coincidence! The hen about whom I started this thread is also an RIR named Bernadette, and who I call Bernie. (You can see her photo above.) Maybe Bernies have an unusual propensity for mood swings!
Anyway, I think my Bernie was traumatized by a combination of factors: predator attack, change in pecking order, and then me leaving for 10 days, and that's why she went a little nuts. I "fixed" her by picking her up and carrying her around with her head pushed down for about an hour a day for a week. It took about 3 weeks altogether, but she finally went back to her old self, and now comes to me to picked up and cuddled like she used to. Good luck!