Brief Answer:
when bile does not have the chance to change, stool can be green

Detailed Answer:
HI, thanks for using healthcare magic

The brown color of stool is due to changes that occur with the bile as it passes through the intestines.
It passes out frequently and quickly then the stool can appear green because the bile does not have the time to undergo the normal changes

The green color can also sometimes be related to the use of certain foods.

If the diarrhea has been persisting for at least 4 weeks then it would be called chronic diarrhea.

Chronic diarrhea has different causes including: (1) irritable bowel syndrome
(2)infection
(3)side effect of medication- if you are currently on any medication, would need to consider checking them to see if diarrhea is listed as a side effect
(4)inflammatory bowel disease- this mainly includes conditions such as crohn's colitis, ulcerative colitis
(5)endocrine disease such as thyroid disease or diabetes
(6)food allergy or sensitivity- a food diary would help determine if it is related to particular foods

To find out the cause of the persistent diarrhea, you would need assessment by your doctor.
This should include physical examination along with blood tests such as: (1)complete blood count,
(2) thyroid ,if this is suspected,
(3)ESR - looks for inflammation in the body- would be increased in infection or inflammatory bowel disease

A sample of stool may also need to be sent to the lab as well.

If testing cannot be done at this time, you can consider the following: (1)eliminating any foods that you suspect may be worsening it
(2)pepto bismol
(3)high fiber diet to bulk up the stool. Use high fiber foods (fruits, vegetables, whole grain foods) and a fiber supplement eg cetrucil, metamucil, benefiber
(4)probiotics- can be used on their own or with certain yogurts

I hope this helps, feel free ask any other questions

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