I haven't had time to read all the responses but wanted to reply before I get too busy at work so forgive me if I repeat what others have said.
I totally understand how you're feeling. It sucks. I have spent a lot of my life feeling "sick" but all the dr's say there is nothing wrong physically. I know the empty feeling inside and the hopelessness. I know the sense of feeling like no one really understands or cares. I have suffered from depression and panick attacks. This thing with your throat closing up may be part of a panick attack. I know the guilt for thinking how shitty your life seems when you know there are people worse off then you. Just because someone else is hurting more than you, it doesn't reduce the amount of misery you are going through.
Which AD are you on?? In my opinion, it isn't working well enough for you. I think I remember reading that you were on Zoloft? I find that one to be the least effective for me. Maybe you should ask your dr about adding one of the tricyclic AD's, they work differently then the SSRI AD's. You may also benefit from a mild tranquilizer like Xanax, to help with the panicky feelings. They will help you to relax and may help both your throat and back.
I started seeing a shrink last spring and it really does help. If your insurance doesn't cover it, there may be some free counsling available, I'm not sure how it works where your at.
I wish I could say something to actually make you feel better but know that you're not the only one to have had these feelings. I really think you need to talk with your dr and tell him how bad you are feeling. Big hugs to you!
-------------------- Taking it one day at a time.....