Hi, I am Dr. Peter and would like to help.
1- Did you see if the skin is rupture on the side of the rectum?
2- Is she rubbing her butt on the floor?
This sounds like she may have a problem (infected) with her anal gland; these are 2 glands inside the rectum; sometimes get infected and clogged up. Not life threatening but could be uncomfortable. It is best to have her checked soon, if this is the anal sac that is infected, it could rupture through the side of the rectum. I would recommend you have her checked sooner then next week. Your vet will do a rectal exam and expressed them, send you home with some meds if they are infected.
If you have additional questions I will be glad to answer them.