Move. Exercise outside. Do it every day. Don't even think about it. Prepare a Alarm and then you just go out and do it. Meet friends. Talk to them in REAL. Leave your Phone and Computers allone as long as possbile.
Sorry to hear about this. If this is the first time you've felt this badly, I would recommend starting with your primary care doctor, they'll be able to help you coordinate the process of getting better.