This is almost exactly the symptoms I experienced. Also, don't feel annoyed at them not believing you about potentially being pregnant. They did the same with me, I said I had zero chance of being pregnant (unless science had changed and two women could now get pregnant), and they still made me do a pregnancy test... So I assume it's just strict procedure.
Thanks for the info, they don't tell you much in hospital...
I was wondering why my belly was so swollen, the air makes sense, as disgusting as the thought of that is.