Hi and welcome to the forum! I am glad that I can help you.
Pain in the abdomen may appear in one of the following conditions: ulcer(the pain is one or two hours after eating during stomach ulcer; in a duodenal intestine ulcer the pain appears before the meal and eases with eating); ileus(obstruction of the bowels due to cancer, hernia, torsion of the bowels, invagination); appendicitis; intestine infections, etc. In the conditions listed above such as in ulcers individuals may vomit blood appearing as a liquid or dark red to black liquid colored like coffee. If there is bleeding in any part of the intestine the feces may be colored with red blood spots or may be colored dark, nearly black. In conditions when individuals bleed a lot, additional symptoms like tachycardia, dizziness and unconsciousness may appear due to hypovolemic shock.
Given the symptoms that you described it seems likely that you may be experiencing an ulcer. You may consider seeing a gastroenterologist for further information about diagnosis and treatment options. You may also consider having a stool bacterial culture taken to rule out infection.
Please keep in mind that I provide medical information only. I am not able to diagnose medical conditions online. Please contact your doctor or other qualified healthcare provider such as a gastroenterologist for further advice and information about diagnosis and treatment options.