Sorry for the delay folks, been acting as nursemaid to a chicken for the last couple of days. Vet couldn't find anything wrong with her and the suggestion was that she may be badly shaken/stressed as a result of being crowded by the sheep. She was quite tender down her right side and over the last couple of days has begun moving around more, albeit a little stiff and uneasy.
Spent Friday in a nestbox, refusing most food (except a little bread with marmite - thanks for the suggestion
) but was happily drinking from a bowl that had to be offered to her.
Yesterday saw a big improvement as she got out of the coop and moved around a bit, although she did have lots of rest periods, but during the evening she perked right up at treat time and mixed it big time with the other girls to get her share
She will hopefully carry on getting back to normal and assume her place back at the top of the order (bad news for Lily who was really liking that position). Thanks for all the advice/comments