 [ Symptoms ] i have been coughing constantly for a few days now and just started coughing up a little bit of blood at first i thought it was i cold i caught from my boyfriend i have been coughing up phlegm with the consistency of slime in one of those science kits they have for kids up until just now it is been yellow green ish but i have been coughing up less and less if anything and it is starting to hurt more and more a few minutes ago i coughed up tiny bit of white phlegm with a little of red in it then again a few seconds later right now my coughs are non productive and hurt my lungs and throat [ Disease ] pepto bismol can cause the stools to be darker but not black and tarry and not likely five minutes after you took it this may be a sign of a gastrointestinal bleed especially the stomach i would strongly suggest that you see or consult your medical provider as soon as possible