Is there a reason for sudden onset of 100% green but well formed stool? no change in diet at all. some nausea. no other sx.

Dietary: There can be many reasons that stool appears to be green. The first and most obvious reason for a stool to be green is from eating green foods. Green, leafy vegetables contain chlorophyll, which could be coloring the stool green. Foods with dark purple coloring, such as kool-aid, popsicles, and gelatin (jell-o), can also result in rainbow-colored stools and iron supplements. Bile leaks as well.