What caused his rectal bleeding with no explanation?

This was extraterrestrial mischief done energetically to be concerning and to distract him. They frequently engage in mischief of this kind. Sometimes the energies are perceived, sometimes not, but they can perturb many different things in the body to varying degrees and they understand that it can lead to inner fear and worry that will limit the person's effectiveness, and it is just the kind of suffering that they like to inflict because they exalt in the ability to inflict pain on others and this is a good measure of their depravity.