Does excessive coughing due to cold and the broncho/rhino virus, which I've had for 3 weeks and doc says it has to run its course, possible cause blood in the stool? I been sick for 3 weeks and have also been drinking a lot of pink grapefruit juice, so a little diarrhea. Tonight, I had diarrhea twice and notice pinkish color in the first episode and red, which seem to be blood to me, in the second episode, and the third episode was clear. No pain, no stomach issues, no fever or anything like that is happening. Could it be excessive coughing causing something or the excessive grapefruit juice?