Thanks for bringing your question to JustAnswer.
Although the self help methods you mentioned, especially EFT, work well for mild cases of anxiety, it sounds like your son has a major depression. Isolation is one of the main symptoms of major depression. This is caused by an imbalance of serotonin in the brain, and responds well to anti-depressant medication.
In addition, giving him the opportunity to talk to a therapist would give him the best chance at a rapid recovery, as the combination of therapy and medication is proven to give the fastest relief from depression. Here's information from the Mayo clinic on depression: http://www.mayoclinic.com/health/depression/DS00175
For a young man in the time of his life when it's normal to spend a lot of time with friends to chose to isolate in his room, is quite serious. Please make him an appointment with a therapist, who can then recommend someone to prescribe anti-depressants.Here's a link to help you find a therapist in your area. http://therapists.psychologytoday.com/rms/prof_search.php