It may just be taking her longer to have the babies. The red discharge is normal, the grey could be normal or not, impossible to tell. If she doesn't seem to be in distress (labored breathing, vocalizing), just leave her alone for a few hours. Disturbing her will stress her out.

If she starts having issues, you're going to have to either take her to a vet, or end her suffering. This is going to disturb some people, but I've had to put down an older female who was really bad off while in labor. I had other mothers with newish litters, so as soon as she was out I opened her up and was able to save 7 of the 11 babies that were in her. I work as a vet tech, so I have experience with surgeries and such, so you may not be comfortable doing that.