Burping with back pain can be due to stomach disorders like gastritis (inflammation of stomach lining), or, stomach ulcer.
People with burping need to be evaluated for hiatal hernia, too.
Constipation is having a bowel movement fewer than three times per week.
Green stool, often results from eating green, leafy vegetables.
Vitamins or supplements, can also cause the green colored stool.
If the stool is also soft, or even diarrhea like, it is expectable to have green color (this happens when the digested food passes through the large intestine too fast to be changed in color).