Sounds like a legitimate digestive problem (possibly caused by anxiety, but not a symptom of an anxiety attack). I've had similar symptoms that came with heartburn and nausea as well. I was also unsure if this was a symptom of anxiety or a digestive problem - I think because the sensations themselves induced hypochondiac-y anxiety so strongly. I switched to an easy-to-digest diet (lack of medical insurance didn't allow for a doctor's visit), to see if it was an ulcer or inflammed intestines. It's been 2 months, and my digestive problems have improved - though my anxiety hasn't.
I get a tightness in my upper abderman and it travels around into my back theres no pain with it just tightness very uncomfortable i have had a ultra scan and bloods taken I also had camara into my tummy but all was clear, my doctor there for puts this down to my anxiety but it is hard for me to except. but then anxiety comes with so many pysical syptoms, Im pleased the meds worked for you, now you should try and not worry take care,
janis.