I will look into the Essiac tea from Mountain Rose.
I do believe what you are saying holds true for many and there is evil, ghost, entities good and bad that roam the earth and do in fact take host enter humans as well as real live parasites.
For myself, it is not a figment of my imagination nor do I think it is evil related but by scientific proof...
I wish more than anything I could just cast them out if you will.
Stress does cause more problems in which it weakens the immune system.