How long after you ate the banana did you start to feel like that? I did the Glucose Tolerance Test years ago when my hypoglycemia was really bad and I almost passed out b/c they had me eat a bunch of dates after fasting for several hours. I literally couldn't stand. I was a bit disoriented as well. They concluded it was Low blood sugar. Might be worth it to try a test. Probably your blood Sugar shot up and then your insulin kicked in too well so your brain didn't get enough glucose. If it's hypoglycemia a Dr. Bruce West has a protocol he always uses with patients with great success & he thinks hypoglycemia is due to long standing B-12 deficiencies. If it's hyperglycemia the ayurvedic herb Gymnema (which means destroyer of sugar) is great for that.