I'd second everything in Goff's post and also offer another bit of advice which might seem insane but worked for me - could you afford to go away for a while? I know the logic of getting yourself on a plane/train, dealing with lots of strangers etc when you're getting constant panic attacks seems ludicrous, but it can really help to get yourself away from your usual surroundings and patterns. I went through a phase of being a total recluse in my teens due to the same problem, and only got out of it by going away for a month and forcing myself to do stuff, even though the shortest conversation was an ordeal. I'm not saying it "cured" me but it really helped me get out of a downward spiral.