Could Blood In Bowels Be Due To Low Carb Diet?

I was prescribed and began taking Metformin 2 weeks ago. At the same time I started a very low carb, ketoegenic diet. I have had diarrhea the past 2 weeks. It is excessive, at some times hourly. I have lost 11 pounds in 9 days and I have syptoms of dehydration - dry, cracked lips and hands. I am also very fatigued - affecting my daily responsibilities. The diarrhea can be described as like hot water - no solids at all. It has been yellow up until today - I had blood. I consider it a lot of blood. I wonder if it is the Metformin I'm taking, the new diet change or both?