Is it like a sinking heavy feeling on your gut/chest? when i used to get it i couldn't/didnt want to leave the house, i'd just curl up on the sofa or visit my safe house the trusted bog lol. always made me feel better sitting on the toilet for unknown reasons! but i'd keel up on the sofa and feel tied but couldn't sleep, start breathing deeply and just wanna be on your own for a bit.
Not sure how i got over that one but i think that was like borderline depression? when i went docs they kept asking me if id ever thought that suicide was the answer!!, they asked it so much it started to keep crossing my mind! not that i would ever do it!
Just have to keep telling yourself, you have an awesome gf, you have a roof over your head, you've got a sweet car and lifes good. You know what helped me learn the values a bit more, one slightly drunk evening, come out of a bar and see a homeless guy with his dog, i sat beside him for a good hour chatting about how he's got there etc... made me value my life alot more, no i've not got everything in the world, but right now i have what i need and thats what makes me happy!
Hope you get it sorted soon, if you ever go docs and they try offer you beta blockers or anything like that don't opt for them. You could also try hypnotherapy which i was offered several times.