She may have a lot of pressure down there as she's getting close. Take her temp and keep a close watch. I wouldn't worry too much about her BM if she's not in distress. Pregnancy and labor being so close can cause all kinds of things in the body to go wonky for awhile. As long as she's not having watery diarrhea, I wouldn't worry. Keep her eating and drinking good so that she has strength for labor. And have the vets phone number and the ER vet number so that you can run to them for a c-section if it is necessary. Many Chi's end up with C-sections, so be ready for that.
"Having heard all of this, you may choose to look the other way.....
but you can never say again that you did not know." William Wilberforce 1759-1833