just been out to have a feel of her crop. all feels normal and she laid an egg! its the most normal looking one we've had for a while. maybe she's cleared herself out a bit.
I've put a ban on the chooks having any treats for a while, they can stick to pellets, corn (afternoon only!) and water with ac vinegar for now.
am airing the spare coop just in case but it looks like I was being over anxious (dopey mare!!)