My horse has been acting strangely....?

I go to a stable once a week for lessons and half lease the horse I use, she's an Arabian. One other girl rides her. She's usually a more spooky kind of horse, and hates being alone, but for the past couple weeks she's been peeing/pooing every minute or so, just a little then will move around a lot and try to get out of her cross ties/slip knot, then start again. I was also having trouble finding bowel sounds. Any ideas?