hi, thank you for your query. The liver secretes a bright green fluid called bile into the small intestine or it is concentrated and stored in the gallbladder.As bile makes its way through to the digestive system it progressively changes color from green to yellow to brown.Green stool often indicates that food has passed through the intestines faster than normal (called decreased bowel transit time), before it could be changed from green to brown. The most common causes for green stools,pain in abdomen are- *Antibiotic use *Medication side effects *Food poisoning *Celiac disease *Ulcerative colitis *Crohn s disease *Malabsorption *Irritable bowel syndrome *Bacterial overgrowth *Infectious diarrhea - especially salmonella and giardia your symptoms mostly point towards IBS,but it would require further investigations to confirm that.till then i would suggest you to start pro-biotics and pre-biotics.these help in promoting the growth of healthy bacteria inside the intestines which help in proper digestion.you can consult your doctor for further details . thank you, wishing you good health