Hello I believe I can help you with your concerns
I am so sorry that your son has been exhibiting this type of behavior, I can imagine how this distresses you to see your son this way
May I ask, for how long has your son been exhibiting this level of paranoia?
And also has he made any threats at all to hurt himself or anyone else in recent memory?
So individuals with paranoia typically will not trust others because they feel other, especially doctors, will hurt them and this is why your son will not voluntarily go get help. Now some cities and counties have crisis stabilization units, that can go to your home to provide onsite mental health evaluation and counseling to your son. Also if your son has made threats or gestures to hurt himself, hurt others, or is considered gravely disabled (e.g. unable to provide for his basic needs like food, clothing, shelter, etc...) then you can call the authorities and he will be placed in mental health hospital or ward for a 72 hour involuntary hold where he will receive an evaluation and treatment. This 72 hour involuntary hold can also be extended by a civil court judge for approximately 21-30 days depending on your jurisdiction
I also would like to recommend this book too, as it can give you insight on your son's situation.
If your son does not meet the criteria for a 72 hour hold, then most likely he will not be willing to go get treatment because his paranoia is just too strong and dominant. This is very unfortunate, but the law can require treatment for those that are sick unless they meet that criteria that I outlined.
*correction: But the law CANNOT require treatment for those that are sick unless they meet that criteria that I outlined
I see that you are offline right now, but when you get back online I would be very interested in continuing this discussion with you and talking about anything further you would like to share regarding your concern, so if you respond in the chat box I will be able to get back to you as soon as possible.