dark brown is normal and not due to a GI bleed
a stool occult blood test can check for sure.
metronidazole gel on the skin most likely would not affect the GI system
most likely something you ate
or a virus or food allergies.
I bet your next bowel movements will be better and more normal
make sure to drink more fluids
let me know if you have other questions.
if done for now, please leave positive rating above the chat box so I can get credit for helping you today
we only get credit for helping clients after positive feedback
you can always reach me with "a question for Dr. David" in the medicine or oncology categories if you have any other questions
here is my website if you need to reach me again:
Thanks for using JustAnswers.com