I had a fox get in with my girls and killed 3 and one that i thought was going to die of shock, i wouldnt move had its head down and overall looked a sorry site. i moved her into a quiete corner of the coop and every couple of hours or so id lift her onto her feet with her head hear the water trough and slowly she came round, it took about 5 days to see any major improvement but she pulled through. we call her " no neck " because of the sorrowful demeanor she showed.
now she is a pain in the posterior, she is the only one who attempts to break into the house through the kitchen window and she bullies the German Shepherd into sharing any treats he gets with her.
i hope you RIR is strong like mine was it certainly sounds like she has started to improve, those Reds are pretty tough girls im sure she will pull through and become a pain in the anyway good luck and god bless.
Del