black stools could indicate blood but it can also mean that you have been taking pepto bismol (the bismuth in this medication causes that stools to be blackish). red-like stools do not necessarily mean blood but it could be. there are special stool tests that will test for the presence of occult (hidden) blood that should be done. four weeks of diarrhea does require a thorough work-up so i am glad that this is being done.
diarrhea for 4 wks. watery and then black stools. now a redish color but not like blood and mucus. is this serious. saw dr waiting for stool culture. had stomach xrays. a lot of gas waiting for ins to get ct scan.