Hi. I am experiencing terrible back pain (all over, including shoulders, lower back and buttocks) and abdominal fullness/protrusion. It feels somewhat as if I m constipated, however, much more severe and I have had no problems going to the bathroom or passing gas. I went to Urgent Care last night (2nd night of pain) and they ran blood tests and did a scan - they found nothing wrong. I m still in incredible pain. In addition, I have spoken to a few co-workers who were with me last week at a conference and some of them are experiencing similar symptoms, although to a lesser degree. Any idea on what the cause could be?