I am 14 years old and have a 13-year-old quarter horse mare named Miss, whom I board. At the stable, horses are always coming and going or switching stalls. When a horse has been removed from the stall next to Missy's, she stops eating and drinking. This happens even if a horse has only been next to her for one day. A few months ago, Missy reacted so badly that she went crazy in her stall and hurt her leg, and now she has a lame leg. Could this be separation anxiety?