Hey there,
I have experienced something very similar to this. My abdominal cramping episodes would last for about an hour every couple of weeks as a result of chronic constipation. I’ve had two colonoscopies and been to countless gastroenterologists only to be diagnosed with IBS. The pain you are describing is extremely similar to mine. I felt like I was dying and it would start with a racing heart, sweating, and a sort of dissociation because of the intense pain I was in. Doctors think it could be a side effect of my antidepressant. Are you on any other medications?