Hi Dear, Thanks for choosing healthcaremagic. The symptoms you mention could be a sign of bleeding from upper gastrointestinal system, it could be acute bleed from gastric or duodenal ulcer. Black, tarry stool could also be due to diet or medications, such as blue berries, dark chocolates etc. Did you have history of duodenal ulcers or did you have symptoms such as feeling pain at the epigastric area when hungry? a pain that relieves with food? or did you have pain that gets worse with food (Gastric ulcer)? Did you take any NSAIDS medications recently such as Ibuprofen,Naproxen etc? If you had any history of upper abdominal pain and now you have a feeling of dizziness, black stools, fresh blood or coffee grounds like vomiting then visit Hospital ER or Gastroenterologist as soon as you can, so the doctors can do the required tests, if there is bleeding then they will treat the cause of the bleed. Don t worry, you are too young to be worried about Colon cancer, and mostly in colon cancer, it would be red flush of blood from anus or an obvious red stool. most colon related bleeding is red in color except if the bleed is on the ascending or transverse colon then it s possible to have brownish or black stool (mostly due to diverticulosis) which again you possibly wouldn t be having at this age. for now you can take Omeprazole 20mg, 3 times a day. until you visit the Hospital. Please don t worry much, today s advanced healthcare system are able to control these kind of bleeding and will get you back to your normal life. It s also possible that your stool color is only due to food,medication(as i mentioned above) and not necessarily bleeding but it s always the good to visit hospital so that you can be checked early and if anything they will control it. Hope this helped. if you have more questions don t hesitate to ask. Wish you all the best.