I have a hen that is 3 months old that I noticed a couple weeks ago laying under the roost in the coop when she got up she was stumbling backwards and then seemed to be limping when walking forward and her tail was drooping down. I brought her in gave her some multi vitamins, and within a couple days she was doing better walking and when I took her outside she ran/flew straight back to the flock! Then a week or so later she was back in the same condition barely able to walk and her tail drooping. Any ideas?!