hi, just wanted to know if the darkening of the urine from taking Metronidazole 500 mg is ok?? iv taken this before but didn't notice it before. i have bit of pain in my stomach which i usually do but haven't got the diarrhea yet. i started taking the pills yesterday evening so only had 3 so far. I'm taking it for infection which is the only pill that gets rid of it! could you let me know asap please. thanks