Ok heres something I have experience with
It is a tape worm. Me and Adam had to do some research on them when one of my CH girls did the same thing some months back. I had one of my girls treated and was told by my vet that
1: They are not caught from feeders. The worm that infest mammals is different than that which infest fish, turtles, and reptiles and are not inter species exchangeable.
2: They are not harmful to humans, just gross
3: They are transfered buy direct contact with feces that carries the parasite eggs. I.E housing animals in one tank and they get on each others poop.
4: These tape worms match their hosts metabolism so for them to present themselves in the feces means the snake has been infested for some time. (bet this was one of your best feeders, never missed a meal but never really gains any weight. Mine was)
5: QT till treatment is done
6: your vet will do a probe kind deal and remove as much of the worm as he can then give an oral wormer. You'll have two rounds of wormer and loads of pooping this gross snot looking stuff out. And one hungry snake when its done
I think I got it all Any specific questions I will try and help!!!!!