 [ Symptoms ] my stool is jet black i have had this before how long does it take for the stomach to digest and pass blood from an ulcer i have got a lengthy history of bleeding gi is which has resulted in multiple hospitalizations for a week or more at a time each time requiring transfusions from anywhere to 9+ and sometimes up to 14 units of blood even though i just noticed it i am already growing weak and getting out of breath for no apparent reason something that never happened this soon before so i was wondering if i have been bleeding in my stomach for a long time and it is just now being expelled [ Disease ] my problems are too many to mention my diagnosis took a dermatologist and an allergy doctor i am allergic to numerous foods and plants trees mold etc allergies can manifest them selves in so many different ways the 40 patch tests at the dermatologists and the food and other scratch tests at the allergy doctors helped tremendously but there are not tests for everything you can be allergic to i am allergic to food additives and preservatives also life is very different now