I have had, I would say, black stools for about 3 days! I'm on Warfarin, my last chk. at cummaden clinic was 2.5, about 3 wks ago! I have high blood pressure in my lungs, which caused me to have A-Fib, and wear a C-Pap! I'm overweight, and have a high stress level, and have had panic attacks since I was 18 yrs. old. I am now 64! I drink alcohol, and have lost about 30 lbs. this year. I had a Colonoscopy in Fall of 2012' that was clear of anything...what could be wrong??