I've Been Have Chest Discomfort For Months Now. My Chest

I've been have chest discomfort for months now. My chest feels like its being squeezed and has a sudden pain that comes and go. I also have difficult breathing where I got shortage of breathe. The shortage of breathe isn't making me grasp for air, but I can't go out without feeling like I can't breathe probably. I have trouble swallowing food time from time and can only drink water because other drinks like orange juice makes me produced lots of saliva in my throat. Sometimes when I feel out of breathe I get pains in my jaw like numbness. Recently I been having a sudden stabbing pain in my left arm. I went to hospitals and clinic to find out what's the problem, but they don't know. Please help me.