The banana cramping sensations started happening to me about 10 years ago when I was already an adult. I found out that eating a slice of bread afterwards OR at anytime the cramping started fixed me right up.
I believe that it's a digestive (intestinal) issue. For some reason, the intestines work overtime doing whatever they're trying to do. Eating bread seems to provide the entire digestive process enough real "bulk" to stabilize the movement of the bananas.
For lack of a better explanation, I think this is what's happening.
I was diagnosed with IBS about 20 years ago. The doctor told me to avoid certain foods, including beans, lettuce, etc. I did so for about a month and slowly started to eat the foods I was told to avoid. Haven't had any issues in 20 years.
One thing the doctor told me was to start running a few times a week. I had always been an avid runner but had stopped for a few years. I started running again regularly - no IBS.
About 10 years ago, I developed the banana cramping. FYI, I figured out that if I eat a slice of bread afterwards or even after the cramping starts - the pain goes away. I think it has to do with providing the digestive tract enough "bulk".