I Had Bloody Stools In Past, But At The Time

I had bloody stools in past, but at the time I was training for a marathon. I had a colonoscopy and I was told I had "runners bowel." I was not a water drinker, therefore I pushed the po fluids and I did fine. That was four years ago. Now for the last 2 months, I have had bloody stools after only running 4-6 miles (comes and goes therefore not every time I run). I run only once a week though. I also noticed that my stools are loose and have a smell. I have a very stressful job and I worry a lot, which I know can play a part in the digestive process.