Well a couple of things. I'm not so sure about the Demonic possession thing. Many of the things which you mentioned are the dramatized symptoms you see on TV. But that's not to say "Something" or "Someone" has not latched onto him. I would look at the history of the Jail he was in and see if there were ever violent deaths there.
It could very well be a trickster spirit trying to make it seem like a demonic possession. I would start by looking at that angle perhaps. Perhaps some murdered inmate looking to have some fun or hitch a ride.
But I would also keep an open mind to a non-paranormal explanation. Perhaps it would be wise for him to seek some help or advice as well. Some of the symptoms almost sound like adult
Tourette Syndrome. You may want to take a look at that to see if it matches what you're describing.
I would use caution for the moment, until you can find some more information.