I Was Put On Macrobid For An Upper UTI On

I was put on macrobid for an upper UTI on the 6th of Nov. Since then I've experienced chronic diarrhea and today was the worst. Very watery and mucus and what may look like blood but can't tell for sure. This has become extremely exhausting and debilitating. What can I do? From what I've read about macrobid, taking anything for the diarrhea will only worsen things. Please help