It is indeed Cabin Fever Time, and Depression Hits BigTime time......Mariner, bagpuss has it. Talk to your doctor, or therapist---this problem can turn into serious stuff, like shooting the neighbors, etc. I doubt there is anything you can do, s/he will just think you are part of the conspiracy, and that would not be good.

Unfortunately, there is not really much that can be done until your friend is proved a "danger to himself or others".