I haven't felt this way, but i know that many do. Those who don't accept this as a real experience, are unfamiliar with powers and pricipalities, in my opinion. I am sorry that you suffer this. It must be very, very scary for you and probably doesn't do a lot for your self esteem. Maybe i'm wrong. Most people would say this is psychosis. I would suggest that you try to side yourself with the positive and tell all these "demons" that you speak of to get lost. Regardless of what we call it, medication can shut off or reduce the unwanted commands. Please try to go another way. If it helps you to think of it as mental illness, well, you have a lot of company. It's some type of breakdown in perceptual filtering, but whether that which is no longer being filtered out [you describe them as "demons"] comes from inside our minds or externally, is difficult to say.