I want to add to just do prune juice one more time, and then begin with slowly adding fiber, starting with perhaps the oat cereal the next day.
I'm 60 and had mastectomy begin of month, so I know what you're going thru. Apparently the prune juice did the trick! It loosened up some of what had collected in your bowels. Try the prune juice again AND drink plenty of water. If you're taking some medications, they can sometimes cause constipation, so review side effects just in case.
Next eat enough fiber, begin slowly, and these include oat cereal, whole wheat bread, cooked fresh or frozen vegies, dark green salads. I myself have to eat at least two of those every day to stay regular becuz I take so many medicines even not related to my cancer drugs. Going for easy walks will also help digestion move more easily, and keep up with the water.
I don't know why you got stopped up. If you continue to be that way towards the end of this week, then go to the clinic, just in case you got an intestinal bacteria floating around in there.