You can find their biography in the BIO section of the public library, titled "The Demonologist". Back in the 70s the Warrens found the crowds at their lectures were very interested in ghosts and hauntings, but as soon as the Warrens started talking about demons, the crowd's temperament changed to skepticism and hostility. Demons are real, don't let anyone sell you on the idea that this is a disembodied human spirit. For all my fellow answerers best intentions, much of what she has taken the time to list is textbook DEMONIC behavior, even according to the Warrens who believed also in ghosts(disembodied human spirits, I do not believe in this phenomena, I personally believe this phenomena is demons or demonic types like familiar spirits who have previously been attached to a human.)
The body is not the spirit, and demons can in fact mess with the body regardless of your spiritual state, from time to time. They can cause muscles to twitch and flex as if you're being given imperceptible shocks that are stimulating your muscles, and some of these actions can be quite elaborate, some testimonies claim waking up to charade-like activities.
It also sounds like you're describing some form of tinnitus, this has been known since antiquity and in modern times as evidence of a demonic spirit at work in your presence, others experience a low vibrational field-like effect in their bodies.
I do not believe it is still inside of you, but I believe if you don't do something to fight it, it will try to ultimately possess you. If it was still inside of you, you'd either be too anti-social to comment on here, or you would be too wicked to care about freeing yourself because you would be under its full influence. The oppression stage can also cause severe anti-social behavior, to isolate you so it has more opportunities to influence you.
If you have any further questions, feel free to ask.