That is a tricky situation. It is great advice from others to check your equipment and check with a vet to make sure there are no medical issues with the horse. After that you may decide that your horse is having a behavioral problem.
If there are no medical or equipment issues, then your horse is just communicating to you with her body. She is telling you (and/or the others) to move away from her. It sounds like you already know how to read her body language, that is good because it is possible that if you don't move away or move her away then the next thing she may do is bite or kick someone to make then listen.
It might be a good idea to find an Excellent trainer in your area to do some ground work with. This could help smooth things out a bit with your mare. If you don't know of anyone in your area, Clinton Anderson has some videos ( I like them, some people don't), or maybe Pat Parelli or Monty Roberts have some videos or youtube clips to help you learn about horse body language and how to influence your horse while on the ground. It sounds like you are taking good care of her, and already are well on your way to understanding her. Hope this helps