Brief Answer:
Your stool color is caused by recent infection.

Detailed Answer:
Hello!

Thank you for the query.

Such color of stool is most likely caused by lack of good bacteria in digestive tract. Please note that bile which is yellow is secreted to duodenum. Yellow bile is changed to brown stercobilinogen by a good intestinal bacteria. Now when you do not have enough of this bacteria or stool passage is too fast (diarrhea), bile can not be completely digested and stool becomes green.
So its not Pepto Bismol caused this but recent infection.
Please keep up with probiotic you are taking and give it some time to get back to normal.

The only reason to concern should be stool black like a tar. In such case, stomach bleeding is the case. But stool is really black. And smells strange.

Hope this will help. Feel free to ask further questions.
Regards.

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