I actually have no ideas, but I get the same thing. Can't yet pin it to any cause except fatigue. I'll be interested to hear what others think. I know if I try to run within 90 min of eating a real meal, I get stomach cramps, but that's different. Low, mid-section, just below the umbilicus, on the left, that's where I get them. Not often, but it reduces me to walking when it happens.