Please Help! My GI Is Stumped. I Have Had Diarrhea

Please help! My GI is stumped. I have had diarrhea since February. All of my labs have come back normal. I have had two ct scans, an ultrasound, a colonoscopy, blood and fecal tests. All normal. However, my symptoms persist. Symptoms include: bloating, cramping, diarrhea, fatigue, weight GAIN, water retention, dry skin, dry brittle hair. If not a GI issue, then what could possibly be the problem? Metabolic? Please help point me in the right direction!