Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner. If you would still like assistance, can you tell me:
Any history of trauma, falls, or injury?
Any chance she could have gotten into a cat fight?
Any outdoor access?
Any changes around her rectum (ie sores, wounds, lumps, tender areas, swelling, redness)?
Does she seem uncomfortable if you lift her tail
or feel her back and legs?