If the stool is just green for a few days this is the Liver Flushing and is fine..do not worry but if you are seeing fuzzy green balls this is a parasite.
The black thing could be flukes. Post on drug support or parasite forum some pictures and maybe someone can identify them.
I hope you are not seeing green fuzzy balls if so get on alkav6 from orizon reasearch .com right away as well.
Cancer patients pass a lot of this particular parasite.