For six weeks I have had a burning feeling in my stomach, which sometimes radiates to my back. The pain is terrible, and keeps me from sleeping or eating. I have trouble breathing at times, and cannot swallow at times, either. It feels like there is a lump in my throat. I burp up a foamy acid-like substance. I have lost weight, probably due to not being able to eat without pain. The doctor has prescribed me to take Nexium, but I am not getting any relief. Now, I just feel sickly all over...just a general feeling of not being well, on top of everthing else. What could this be?